Shimano 1x10 speed help

Hi,

First off, apologies because this is a ramble, but I'm going round the houses on what is the best (sensible?) option.

My son has a 2022 Kona Dew Plus (1x10 - RD-M5120, CS-M4100 and SL-M4100) which has a Shimano 68mm Square Taper Bottom Bracket, and Samox 36t cranks.

1. The bike needs a new cassette (worn) and shifter (broken).
2. Son wants a larger chainring (42t), as he's only using the bottom couple of cassette sprokets.  The chainring is welded to the crank so my understanding is I need to buy new cranks which use bolts to attach a chainring, then get a larger chainring.

Now, I have a cues CS-LG400-10 cassette in the shed, and I know deore and cues are not cross compatible, but I can't stop thinking...maybe it would work if I just swapped out the CS-M4100 and used the CS-LG400.

I'm wondering would any of the following work (what with me having the LG400):

• RD-M5120, CS-LG400 and SL-M4100 with an 11 speed chain
• RD-M5120, CS-LG400 and SL-U6000-10R with an 11 speed chain

or, 

• Keep fully Deore and replace the cassette and shifter like for like (so have the original RD-M5120, CS-M4100 and SL-M4100)

On the larger chainring, I had a Google and as an example I found a SURIEEN 42T Mountain Bike 170mm Square Crankset, but I've no idea if thats a good option, or if I should be looking elsewhere. (I've seen CUES chainsets so wondering if I could use that?)

I know....all over the place!  I guess, unless someone has a good option, I'll just go with replacing like for like, and keep the CS-LG400 in the shed.

Thanks