His denial actually makes the warnings more credible. For a while I was worried why they'd all agree.
In my opinion, social media is not the biggest threat to kids - algorithms are. I fully support the SoMe restrictions on kids, but could possibly accept a fediverse partition if the server would be maintained by the community, school or some trustworthy non-profit.
Guessing. To my limited understanding it relies on 32bit OpenGL drivers. Or later they made vulkan support, but that needs to be enabled via custom launch option "-vulkan"