What's the bare minimum for a VTT?

[Nikosandros]

Maps and tokens. Basically, the 'tabletop'.

Everything else, you can easily handle yourself. You can roll your own dice, track your own initiative, use a character sheet, chat through Zoom etc. The basic thing that you can't easily do on your own is a shared battlemap and tokens. That's the basic premise of a VTT--everything else is bells and whistles. Awesome bells and whistles, of course, and very nice to have, but the basic function of a VTT is the shared tabletop.

This. I would add some kind of fog of war, so as to reveal the map as it is explored. Owlbear Rodeo delivers it and is what I've been using.