I've done a lot of things reusing/modifying the internals of alacritty [1] to put terminals in things. TeX in the terminal [2], a terminal in minecraft [3], Alacritty in Godot [4], and not pictured, alacritty in a swift plugin for macos/ios/ipados all at various levels of completion.

1. https://alacritty.org/

2. https://blog.fangorn.io/tex-in-terminal

3. https://anvil.fangorn.io/fangorn/huorn-minecraft

4. https://blog.fangorn.io/alacritty-in-godot