It's almost the same as plain Android, only with the Google services removed or locked down, and additional security restrictions and permissions control. Most apps work without any additional configuration, unless they're doing something unusual.

The only supported devices are Pixels, so take your pick from the list: https://grapheneos.org/faq#supported-devices

No programming knowledge required.

Graphene only supports Pixels due to the titan chip. The versions with "a" are cheaper. Check when they go end of life to find the cheapest if you care about updates. So probably the 6a or 7a if you want at least 2 years of updates.

It's pretty dummy friendly. Accept that some things may not work or will work differently (Most notably tap to pay is a no go AFAIK,) and be willing to learn if something comes up would probably be how I describe it. The only problem that might turn up that an app that you need doesn't pass gOS' security checks, but there's an app level setting to lessen security restrictions if it's something you NEED.

Otherwise, meh? Flashing back to stock is super easy via a google web tool if you don't like it. (I had to for a trip, Ticketmaster was being wonky and all my shows were ticketmaster haha. I've never had a problem before with the Ticketmaster app so IDK if it's an ongoing thing or not)