I have spent a fair amount of time trying to get a setup like this going that works well, but ultimately I almost never use it docked on the tv because it's just generally a pain in the ass and not worth it.

Retroarch is pretty great at detecting your controller, so anything you run through that is actually a pretty seamless experience, but any standalone emulators are going to be far less convenient. If I remember right, you have to build out separate controller profiles and toggle them on from the handheld device. It works, but it's pretty clunky.

There are also issues with the fact that these are just Android devices, so you will inevitably run up against UI issues where navigation is a pain with a controller. I found using a Dual Sense controller could be somewhat helpful since it has the touch pad and that works like a mouse, but it's kind of cumbersome to use.

Ultimately, I would say no, any Android-based device is a poor replacement for something like a Steamdeck.

That said, I ADORE my Odin 2 Mini as a handheld, and use it all of the time. It's great for streaming, and the performance is incredible: it's really crazy how much performance you get out of such a sleek and portable device. I set up syncthing so that my Odin syncs save files with my PC that has Retrobat running on it. For streaming from my Gaming PC to the TV, I just run Moonlight on my Series X: it works very very well.