I run HA on a RPI4 with lots of integrations, addons and it is running smoothly. Personally I looked at several NUCs and while they indeed have way more power, as far as I can tell they also consume way more power, so the running cost are higher. That is why I chose the Raspberry and a SSD. It has enough horsepower for me. I run Hassos so maintenance is a breeze.
I own a Somfy Tahoma and it works. I use the cloud integration (local is still in development). With RTS blinds it has its limitations (e.g.it will go in a blocking timer while the blind moves, so it will temporarily stop responding to other commands). Also cloud sometimes gave me connection problems, but not lately.
If you only use Somfy RTS blinds/screens and are not afraid to do some (fairly easy) tinkering I would recommend ESPSomfyRTS. It has the advantage it is very cheap and also keeps the blind position, which Tahoma does not. You can control the sun sensor from it too. Downside is it cannot control IO blinds. For that you need the original Somfy stuff. As far as I know neiter can use the sun sensor directly to controlother stuff, but you could tie other blinds to the sunscreen. I use a separate lux sensor which gives way more flexibility.
I also own Motion Blinds. I use it reliably for quite some time now, but the integration mentioned above requires the Motion Blinds wifi bridge. I have the round one, there’s also a cheaper one.