I still check HLTB before starting any play through. My only gripe with it is the average time to beat always seems too low. Like these folks are speed running through it. Or maybe I’m just a slow gamer lol Either way I just add 20% to whatever the listed time is and that typically is accurate enough for me.
If you have access to a Windows machine, that is the easiest method. Setup everything as you want it, with Mod Organizer 2 (portable), on the Windows machine. Then use the Linux installer of MO2 on your Steam Deck. Overwrite the contents on your Deck with the directories from your Windows machine. You may need to mess with the path arguments in Steam to open MO2 when running Fallout.
I’ve heard you can mod directly from the Deck, but it’s more tedious. I haven’t done it this way, so I have no advice.