Selling a bike - should I? (Gravel content)

The secondhand market is cheap at the mo, but there should be reasonable demand for your ti bike - and you can probably pick up a nice, lightly used carbon road bike for less than you sell the Camino for.

I have a gravel bike and a carbon road bike, they do feel a world apart in terms of speed and gearing (I'm 1x on gravel).

How would you envisage a road bike to be different to the camino ti with different tyres?

Is it 1x ?  2x is better for road riding because you'll have less of a jump between gears.

The gravel bike is 1 x 11

If it was me I would turn one gravel bike into a more road orientated bike. The second hand market is cheap at the moment so you wouldn't be getting loads by selling it (albeit as stated you should get more as it's Ti).
However doing a "light" conversion means you can fettle in the garage for a few evenings to your heart's content, and whilst you will end up spending more on parts, man maths states this is a saving over buying yet another bike...

1 x 11 would bug the hell out of me on a road bike.  May be worth popping on a 2x GRX chainset and fitting a smaller cassette. Just change the tyres and it will be a good road bike. Also new LH brifter and a front mech.

Road bike isn't really one category these days (was it ever?)

"Endurance" types will be very similar to the Camino. "Race" types will feel much snappier, faster steering, possibly less comfortable. Depending on your requirement I'd look at changing the Camino to 2x, fitting some nice wheels and tyres and enjoying the build process. 

2 gravel bikes here, one at the road end of the spectrum - Spesh Diverge, carbon, with good carbon wheels (700 x 42) and one much more MTB orientated - Carbon Topstsone Lefty, 650 x 47.  I find they get about equal use, and are the main bikes I ride these days.
I could get by with one of course, but they don't overlap as much as I though they might.

I have considered selling the Topstone, but as others have said, I wouldn't get much for it compared to what it cost me.

I do also have 2 road bikes, a carbon Synapse and a Spesh Creo SL

I'm a bit in the same thought process, although it's do I buy a nice road tubeless wheelset & slicks for my gravel bike or a s/h road bike.

I like my gravel bike, it's carbon and light/stiff etc but as it's 1x it just lacks top-end gearing.

I've no space issues and already have a range of other bikes, just nothing road-wise.

1 x 11 would bug the hell out of me on a road bike.

I found it great but I don't live in the mountains. I was using a 44t with an 11 - 26 close spaced cassette so none of these gaps that people talk about as a negative as cassette was 11-12-13-14-15-16-17-19-21-23-26

I think it depends on what you want out of a road bike. I'm overweight, slow and perpetually injured, but when I'm on a road bike I still think like a 'proper' roadie, it's all about long climbs, prolonged efforts on the flats, chasing segments, cornering on the drops, puppy paws and TT positions on the flats etc.

My gravel bike with slick tyres (10kg, steel frame, 32mm GP4seasons) isn't really much slower but just doesn't reward those behaviours in the same way, it sort of just stolidly gets on with it. I'll use the slicked up gravel bike for Audaxes etc. but for a typically sunny weekend ride I'll always reach for the road bike (2kg lighter, stiffer, waxed drivetrain, 28mm GP5000s, latex tubes etc).

Or just to throw another option into the mix, my first gravel bike has become my winter gravel bike, indistinguishable from a CX bike but wider tyres, slightly wider gear range and bottle cages 😎 It's such a fun bike to have in the garage as it really rewards going out and looking for truly ridiculous muddy singletrack and getting it sideways everywhere. Wouldn't be without it at this time of year.

New pure road tyres on one then sell it when it gets warm

I'm based near the lakes, so I would like to tackle some of the bigger passes (not full on Fred Whitton) but maybe a couple each time.  It seems a shame to not use the Sonder for its intended purpose, but it's not getting used. 

But a few tweeks and would it become a capable road bike given the geometry (its the V2)?

The  1x11 on my road Kinesis works well around here: 11-42 cassette, came with a 44t front, which I dropped to 42t then 40t.

But it's all up or down around here (SW Wales) and I'm usually in one of the 3 gears at either end of the cassette, never hunting for anything perfect in the middle. I'd hate it around Oxfordshire where I used to live, and that bike lasted exactly one ride on Zwift for gearing reasons too. As for spinning out, I often see around 40mph on the downhills, which is plenty enough for me.

Head angle of 69 degrees means that Camino will never handle like a road bike. What's the other one? You will want a head angle of 72 degrees or more for proper handling. However decent wheels and nice tyres will make a big difference
As for 1x11, well one of mine (titanium cross bike) is running 38x11-28 and the gears are nice and close together (closer than running a semi-compact with a 50T outer in fact). You might struggle up some serious hills on 38x28, but I find it a decent compromise for relatively modest climbs (not mountains). You'll be coasting down some of the longer descents but it's not been a huge issue. It manages medium paced club rides fine (>20 mph average). Wheels are handbuilt, Dura Ace hubs and Mavic CXP33 rims, with 30c GP5000s and latex tubes. Weight is < 8 kg.

I had the same dilemma,  I decided to set one up for for off road / explore mode and one for mild off road / know the terrain mode ,   but a slightly more road biased set up. Fenders and faster rolling tyres.
Once it's gone it's gone....
I suppose it depends on what riding you enjoy and the length of rides etc.