There are a number of places to get switch accessible games/resources out there, and some initiatives looking into gaming for people with disabilities.
The Peepo website provides resources and games targeted at people with learning difficulties.
Loads of excellent, fun, motivating free switch accessible resources:
Meldeth Manor School have produced a range of switch accessible Multimedia.
An excellent resource of some classic switch accessible games, for free:
This new website includes some switch accessible resources for people with special educational needs.
Some useful, simple but motivating switch accessible games - there are a range of resources that progress up levels of ability:
Resources for Sensory Software’s Grid2 program.
Resources for Clicker5.
Standard games that might be controllable with the right interface/on-screen-keyboard
The GameOn project: “Some young people with disabilities miss out on the opportunities provided by computer-based games and leisure software because they can’t control joysticks or other gaming devices. It’s these young people that the award-winning GameOn! project intends to help.”