Honestly, isolate what your fixing, not the scope or at least not the big metal chassis scopes. Metered helps a lot.
I made a 3A non-isolated variac connected to a 1200 W isolation transformer. I had the switch arranged so it would go through the 3A variac, off or isolation. I really didn't think ground through, but I also put binding posts on the unit and a fuse on the front. It's worked fine since my early teens.
Most of my uses were on old TV chassis that were not isolated. The second use, was bringing up power amplifiers where isolation generally wasn't needed.