No idea who spreads the word of dual booting. I went into that trap as well. I’ve spent so much time on grub. Don’t waste your time. Even if you manage to fix it after hours, you are not better off than before. You will run into the same or another issue again. And you won’t remember what worked did before. Backup your stuff an run.
Nowadays I use an atomic/immutable system but I wouldn’t do it on a traditional install differently.
Install all packages as flatpak
Server stuff is installed with podman (docker in the past)
Whatever is not available as flatpak is installed via distrobox