Some ideas:
Starting with viewing:
- This can view CR2 files, but I don’t know if it handles CR3 https://www.xnview.com/en/
Organizing and batch processing (not free):
- Long time ago in a land far away I used Thumbs Plus
Free alternative to LightRoom:
- I don’t know if DarkTable might work, but the price is right.
Paid alternative to LightRoom:
- Or, of course, there is Luminar