Unity is Unreal Engine's biggest competitor by far. Godot competes with Unity (mostly for 2D games) but is at least a decade off being any threat to Unreal.

So yes, funding Godot is A Nice Thing To Do but it also conveniently puts a bit of pressure on Unity, their biggest competitor, without impacting their own business.

Also, if you believe Matthew Ball's take[0] then Epic is all-in on fostering as many gamedev-ish creators as it can so that it can loop them all into making content for its metaverse later. As you alluded to, in the long term funding a FOSS game engine which is focused on ease of use helps that too.

[0]: https://www.matthewball.co/all/epicgamesprimermaster