Are there standards for tubeless tires/rims?
Basically at this point there's broad cross-compatibility in practice  among the tubeless compatible me-too type "systems" by way of everyone just copying each others bead and bead lock designs. A de facto tubeless standard emerged from all of it that more or less just works.

UST is an exception in that it's a clearly defined system in terms of the dimensions of both the rim, the bead, and other specifications like how the rim has to be airtight by itself. But UST has other issues, namely that for all the trouble one goes through to adhere to it, you get a heavier tire and no puncture-sealing if you run it without sealant, so it's pretty far out of favor. Using non-UST tubeless tires on UST rims and vice versa set up tubeless usually works fine, but requires sealant.