I did the same thing with my RB button on my LCD model. I went the official repair route, which cost $130. If you can solder you can probably just replace it yourself, I just didn't feel confident enough to do it.
I wouldn't buy it to replace my phone. I want to keep that and my gaming devices separate.
I would buy it a dedicated handheld in a similar form factor to a phone + some controls. I've actually been looking at the AYN Thor for this exact use case. It would have to be the right price too.
I just hope it's more finished than a majority of these driving games. Long Drive is unfinished and it's multiplayer is terrible. Drive Beyond Horizons is better but runs like crap and still super buggy.
Steam Deck can run Forza 5 okay enough, just don't expect it to look amazing, especially while docked. It won't be at the Xbox in terms of visuals and performance.
Based on how Motorsport ran on PC, I wouldn't count on it being a smooth experience for FH6 until we are proven otherwise.
Also you can stream you main PC to a steam deck, although you're going to want a wired connection if possible, especially if doing so while docked.
I know a lot of you don't care if these games run or not, but really does suck they don't. I've talked to quite a few people that wouldn't switch to Linux because X game doesn't run on it.
If it was $60 it would be an instant buy for me. $80 I would consider it after a few weeks of reviews and such. $100 is just too much.