You 99% won't brick it, I guarantee you. Graphene's install is really easy. You press a few buttons on a website and never touch a terminal, aside from if you're on GNOME. As for price, I got a used Pixel 4a 5g for 100 and newer ones won't be as expensive as the things you might've gone for. Try a used Pixel 6a? (Graphene doesn't extend software support)
I got a Pixel 3a for 50 bucks once (really good deal, a few circumstances around it) and an OEM unlockable 4a 5g for 100, so under the category you gave and in some sense more sustainable (its used), able to be degoogled,
Personally I don't, it's been a while and my usage was never too professional. A quick web search doesn't seem to show anything, though that's probably due to the video editor's obscurity.
I'm looking on Mobilism for stuff and all the forum comments make the releases seem suspicious