I haven't used it myself. But a thread on CTC forums says bike bookings now live. Previously buses carried bikes at the discretion of the driver. Pot luck.
And here:
https://www.highland.gov.uk/news/article/15052/bikes_on_buses_scheme_extended_to_meet_demand
Also Ember buses between Glasgow & Dundee or Edinburgh & Dundee - which are also electric.
https://www.ember.to/
Also Flixbus now in UK, who will also take a bike:
https://www.flixbus.co.uk/service/bike-travel
And trains are now finally starting to create more spaces, not sure if online booking is fully working easily yet though.
https://www.scotrail.co.uk/plan-your-journey/cycling/bikes-trains
Fort William train drivers have been getting trained this week on driving 153 units that can carry more bikes so hopefully they will enter service sometime soon on the West Highland line. They have been used on the Oban line last season.
