This is a totally unsatisfying answer, but your only actual recourse, if you want to keep using steam, is to reach out to them and express your displeasure at their updated TOS and its implications.
Valve's TOS hasn't actually changed. The new law just requires them to more clearly disclose that a license is not ownership, but that was always the case.
No. I don't trust another corporate-owned platform, and I don't trust the way they pay lip service to federation while still making everything dependent on one central server they control.