So we recommend branch per fork, merge what you like.
You have to change the branch on each fork individually currently and thats unlikely to change in the short term due to the complexity of git internals, but its not that hard to do yourself `git checkout -b fork-{whateverDiscriminator}`
Have you considered git worktree?
Great for simple things, but git worktrees don't work when you have to fork processes like postgres/complex apps.