It's not a bad option, but probably the best choice would be to just buy a new Framework entirely and sell the old one. Other than other home-labbers I'm not sure who'd be interested in buying a last-generation Framework mainboard, as anyone with a Framework already would likely upgrade to the latest.
Big laptops aren't really my thing, but you may be interested in the 16-inch Framework that's coming out as it has a slot for a dedicated GPU.