Copying my reply from the c/food community here for visibility
I am for a merge. It worked well for my communities to merge (PlayStation and PS5) and I think it will be successful here also. I chose to keep my PS5 community open, but since you are dealing with merging multiple communities it might be good to lock them with a pinned post for at least a little while.
Once the dust settles I think opening them back up (but keeping the pinned post) would be a good option to give the choice back to the community for those that eventually wish to splinter off.