In Unity, I have my game passed onto a render texture at 64x64 and projecting onto an ingame tv. The environment is static, non-interactable and is only there for aesthetics as well as reducing eye strain for fast low resolution movement.

Is this still considered in the spirit of the jam as the game itself is 64x64? Or does the entirety of the visuals also need to fit onto a 64x64 screen?

People keep finding ways to bend the rules, lol!

While you're technically rendering a game to 64x64, you're rendering a scene around it as well. It's generally been agreed that black empty borders are OK, and the rules state you can render a graphical border if it's on the web-page rather than in the game... I mean, you can do it if you like, at the end of the day "authenticity (use of 64x64resolution)"  is a thing people will be rating on. so people may interporate that in your favour, or not... ;)

Hm, in that case I think I'll make an option that will toggle the 3d environment. Thank you for taking the time to answer.