How to find a "virtual" mathematics conference?

Mathematics research is mostly published in journals, sometimes books. Not conferences. Submit your papers to journals instead. You do not need to travel or speak to do that.

Conferences in mathematics are pretty much exclusively an affair of presenting your own research live in front of a mostly captive audience, and talking to the other participants between the presentations. A "virtual conference" (an online list of notes?) fills none of the missions, so I do not expect many to exist.

Even things called "proceedings" work much more like journals than conferences, to my knowledge. Most conferences have no proceedings — at best a list of abstracts online, perhaps even a copy of the slides if any.

(I have heard of (one) conference happening in two cities with live retransmission of talks from city A to city B and vice-versa, but that does not seem to be what you are looking for.)