It isn't too hard. I'm using flavours as my colorscheme manager. I set wallpapers with my own small python script. It's generating colorscheme with material color utilities package from passed image, overwriting colorscheme file in flavours colorschemes folder and setting wallpaper through hyprpaper. quite simple. script itself.
Also I thought of creating app for managing material you colorscheming, but haven't done it. Maybe one day...
I've never heard of AGS before, it looks great! I was planning to switch to Eww once system tray support was merged, but this might be easier. How much have you customized it to get it like this?
I really like terminal apps, but prefer gui ones. I'm little tired of neovim and now switched to vsc, but I still use it sometimes. Also I am still using terminal fm's such as joshuto or lf.