RetroAchievements for Terraria require tModLoader, which you normally can't run on Android. I tried getting it to work with GameNative, but had no success.
But recently, I discovered this Android app that lets you run desktop .NET apps:
https://github.com/FireworkSky/RotatingartLauncher
The installation is pretty straightforward: you just specify the path to the GOG Linux version of Terraria and the path to a ZIP file containing tModLoader.
For mods, I downloaded them on my PC through Steam and simply copied the .tmod files to:
<Internal storage>/RALauncher/Terraria/tModLoader/Mods
For save files, I set up Syncthing to sync ~/.local/share/Terraria/tModLoader/ to: <Internal storage>/RALauncher/Terraria/tModLoader
By default, the game opens stretched at a much lower resolution, but going to Settings -> Video -> Fullscreen automatically sets the correct resolution.
To log in to RetroAchievements, I had to connect a keyboard to enter my username and password. While doing so, I noticed a small bug: connecting a keyboard while the game is running crashes it.
I haven't seen this app mentioned on Lemmy, so I hope someone finds this useful.
P.S. The handheld in the picture is an AYN Thor.
Does the gameplay feel OK? No stuttering or anything? Is it better than just running the native android app? Also, which version of the Thor do you have?
Yes, it runs great without breaking a sweat.
It allows me to run tModLoader, which I can't do with the Android version of the game.
I have the 12 GB version. I bought it at launch.