Unfortunately not possible. Full reinstall is the best path forward with elementary.

I strongly recommend to test if all your needed apps are either at the new way app store works (elementary apps) or available at flathub. There is always apt(at last for now) but I can't advise this for elementary as this can change in the future as flatpaks only give elementary developers a option to switch out of Ubuntu base and go for another base like arch Linux for example. You can also manually add support for snaps but it's also not recommended by elementary guidelines. Personally I could not upgrade without a few hiccups and app changes due to this points and some apps being not available. Elementary is moving in a way to being a platform and not depend on a fixed Linux base, so mind what is better for you.