I should have mentioned that I've sidestepped the whole topic of co-installability of pkgs fuse and fuse3. Despite closure of # 912528, on my Sid system fuse3 3.4.1-1 has an explicit "breaks" on pkg fuse. At least, that appears to be why installing fuse3 requires removing fuse. I could be missing something. Resolution of that situation could make gvfs-fuse versioned dep on fuse a moot point. My suggestion assumes no resolution of that situation and just deals with things as they are.
-- James Ronald Lovell <ron163...@gmail.com> Huntsville, AL, USA