I randomly came across a widescreen patch for Angels vs Devils. After testing it and confirming by myself that it does work I decided to share it here. It was created by AlphaYellow and can be downloaded on PCGamingWiki. Remember to also install the FOV Fix, as mentioned in the notes below the instructions. For Hex editing I recommend using HexEd.it.

Below you can see some screenshots I took while testing out this patch. Unfortunately it makes the HUD a little messed up, and it also makes character models viewed in main menu and in 3D portraits squished. It's a little annoying, but other than that, it's perfectly playable.