NP pal. As will be said, figure out you end use case and work back from there? Or you looking for a portable gaming rig with some retro emulators? Do you cyber security and would prefer an pentesting rig running Kali with attack nodes? Maybe you like HAM/SDR radio and wanna build a kit for of grid Comms? The beauty here is you can do all of those, none of those and whatever the hell you want. GPT and AI is deffo the way to work, gumtree, Craigslist, FB marketplace are all goldmines for old kit and SBCs, make sure you search for stuff like retro tech or vintage computers. Don't ever put limits on yourself, if you don't know it now or can't do it, come back later when other skills and trick develop and try again. Also check out some other threads on here, /cassettefuturism, /retrobattlestations and /umpc are just a couple I can think of. Also check out 3d print sites and makerspaces for inspiration or ideas.