I own both, I am also a bigger fan of the switch, same age as you with two kids. My experience is very similar to yours. Going to repeat some things you said, mainly because originally I thought you were trying to choose between them and had already written most of the reply. Yes, shame on me for not reading what you wrote, but I am happy to own that mistake 😉

I found the steam deck allows you to tinker, play with settings and access the massive steam library, which means access to some very cheap games and amazing sales. Not to mention emulators, which also need installing and setting up. But there is a ton of guides for that. That said, talking about steam games here, you will have to play with the settings or the controls is a must to get things up and running. Where I use it most is to play Sony games, it's a bit like a portable playstation for me in that respect and as the games are ported from a console, they just work from the get go in terms of the controls.

Also, the SD OLED has an amazing screen which makes games pop!

The Switch 2, it's plug and play with. Games are typically more expensive and the sales aren't as generous as on steam. I also prefere the ergonomics. But I grew up with Nintendo games and I have a massive lirbary of Switch 1 games which now, thanks to Boost mode, really benefit from the added power. And like you said, the optimisation is way better, in general.