Backing this stuff up is really difficult. The vast majority of macs don’t have enough storage to keep everything local. If you put it on an external drive then it disables some features.
My solution is to keep an old Mac as a backup device that keeps all the files local and backs them up. But that’s far more than most people are prepared to do.
Switching to Linux won’t save you if Microsoft Edge takes such a huge market share that a lot of the internet starts to basically require it.