Upconverting VCR to 4K picture will be a fake 4K. Noise filters and other corrections will try to re-create pixels missing on VCR, but they can only do so much. At the very best, they will make VCR tolerable on 4K screen.
There is also a matter of convenience. Even DVD remote feels sluggish, limited functionality and lame menus, compared to watching files on HDD. VCR is one yet step below. When I open some show on HDD, it opens the list of thumbs-seasons, click on the season opens list of thumbs-episodes. Same with music - click on Classic opens the gallery with thumbs of composers, click on composer opens list of album thumbs. With DVD/CD you have to open the shelf and find what you need, shows and movies in fine print on the narrow 1/4 edges.
TV speakers suck, all of them. Sound worse than in $4 earbuds. I tried to find half-decent compact speakers for RV, something smaller than B652, to hang on the wall.
Polk S10 at 6"x5" front looks small enough. Now need to convince myself that 6 times the cost is worth it.