@pixouls I have the skills and permission to do things like that in my own time from my employer but I haven't done it so far.
I'd definitely be interested in starting though.
I don't have much in the way of references but here's a talk about the easier parts of accessibility testing that I held in 2020: https://media.ccc.de/v/rc3-734096-building_less_in_accessible_web_sites
(My mic died during the talk, so the audio quality is not great sadly)
@dysphoricunicorn thanks for sharing! If you end up establishing your own services I will stay tuned !!