I've got the OG model, and it's still the main device hooked up to my TV. All my TV streaming goes through it (mostly Jellyfin these days), and it can stream games no problem via Moonlight.
It's hooked up to a 4k LG TV, and I have no idea about how it does the upscaling, but 720p content looks perfectly fine on it.
Best (worst?) of all... it still gets updates.
+1 for Projectivy.
After the ADHD-inducing default Android TV interface, Projectivy is just beautifully clean and simple.
I have quite a few Android TV (or are they called Google TV these days?) devices, and they all get the Projectivy makeover. The TCL TV running Android needs some 'adb' commands run so that the users selection of launcher is maintained across reboots, bit other than that it's been smooth.
The only two complaints about mine is the one set of updates about 5 years ago that killed every connection to my NAS, and that the auto skip function for credits doesn't know if there are scenes after the credits.
But overall, for running it for like 9 years with a cost of less than $200 and essentially zero maintenance, the shield is awesome.
Yeah I just loved the one where they forced ads on the homescreen. Now I use ProjectIvy