How many add-ons are we talking here?
You could copy the user configuration and just nuke the folders under the addons folder that have addons you either don't want or know to be incompatible. So far it seems that 2021.1 is disabling incompatible add-ons anyway (or it did for me, and suggested I remove those).
Brian - Windows 10, 64-Bit, Version 21H1, Build 19043
I do not understand why some seek to separate a person from their actions. The self is composed of an individual’s thoughts, actions, and expression, which are contained in and actuated by the body. What you do and say is the clearest indicator of who you are.
~ Brian Vogel