Do it! I switched from iOS to a Google 4a last week, and have flashed my phone with CalyxOS. I was very tempted by GrapheneOS, but having microg built into Calyx has meant the very few apps I want that aren't on fdroid work perfectly fine for me (so far, these are my banking apps).

CalyxOS turned out to be about perfect for my use case, and I've been incredibly happy with it.

They have a flashing tool, which basically involved me plugging my phone into my laptop and running a script. Only thing I really needed to do was follow the prompts.