I'm curious on this topic as well, considering I have a 13" MacBook Air on it's way. So far, the only major browser with native Apple Silicon support is Firefox Nightly - it's packages as an Universal app. Firefox Dev and Beta releases are still Intel only. I downloaded and looked at Google Chrome Canary and Microsoft Edge Canary, both version 88, and they are also still Intel only.
I'm quite surprised that neither Microsoft or Google wouldn't have at least beta versions of their browsers available for day 1. I'm sure they have access to the Developer Kit mini's with the A12z chips that they could have compiled and tested against. Big Sur has been stable enough for the last two months or so where they could have started development and be far enough along where they could at least have the dev or beta versions available.