I am an occasional user, just for fun. Bought the paid Pro version over a year ago for around $200 (a fair value) and it expired since. The options have changed since:
SketchUp Free: Does this allow me to save models on my PC?
ShetchUp Go: the only difference is ipad capability (which I don’t use), unlth 3d warehouse and unltd cloud storage (which I don’t need since I intend to save on my pc)
Sketchup Pro: $349 is a bit steep considering the little work I do on it (maybe 3-4 models per year only)
You can download Sketchup files to your computer but the normal save location will be in your Trimble Connect cloud storage.
There’s more to it than that but asa hobbyist user you may not need the features.
I would suggest trying Sketchup Free for a while and see how you go. Maybe that’s all you need. If you decide you need the additional capabilities of Go or Pro later, you can always upgrade then.