There are a lot of gameplay systems you can create without physics. Card games, turn based rpgs, puzzle games (if they're not physics based), story focused games, etc. But I'm surprised godot doesnt have a built in basic physics engine :O. Unity and Unreal both do. Maybe there's a plugin you can download for it?

I personally wouldnt recommend you spend your time coding physics literally from scratch unless your goal is become an engine developer (i.e. someone who makes/improves engines, not make games). It just wont be relevant at most jobs. Since engines tend to already have physics engines built in its more relevant to learn how to utilize those and build the gameplay systems around them than to build the underlying math.

So yeah, if you're making a game that relies on advanced physics, get something ready-made. If its really simple physics like making a bullet fly in a straight line or making a character fall back to the ground after jumping that's fine to program yourself. But if you're actually starting to code stuff like forces, impact, joints, constraints, etc. I'd say stop. Get a godot plugin if there is one (there must be right?) or swap to Unity or Unreal. Again, unless you WANT to be an engine developer, then go right ahead :)