I don’t think we need to play Whack-a-Mole or fork everything. We can instead support those developers who make clear that they are supporting ClassicPress.
In the case of page builders, one of the Beaver Builder devs has already made it clear on these forums that they will be supporting ClassicPress. See "Must Have" Plugins List - #40 by Pross
Obviously, changing from one plugin to another takes time and work in the short term. But, if it also provides a long-term solution, then it will save both in the long run.