tcjur Hi. Maybe I am too pessimistic. But this forum (both "General" and "Mojave Beta" (!)) are full of comments: Comments written direct to Anthony, requests for a Big Sur update, ideas about fundings, selling/buying the code of MH, and much much more - for months! All comments in the same direction - to bring MH back to the users which also would love to pay for updates (of course!).
If Anthony has not heard/read about the feedback and the wish/hope to see "MH for Big Sur" until now, he would also not read/hear the "+1" action. It would just disturb those who receive lots of status updates (New comment was made blabla ...) about this forum. In case Anthony follows this forum and reads the comments then he knows about the importance of MH for many users. It is his decision what happens (or not happens) to MH.
I am sorry, but you should give up the hope for seeing a MH for Big Sur. Nothing comes from Anthony - who is responsible for MH. The most up-to-date version is v1150 or 1151 (if I remember correct), from autumn last year (!), and still a beta version - compatible with MacOS Catalina. It is not possible anymore to buy MH from the MH homepage, even not for older MacOS (as a person in this forum mentioned).
I heard from other developers about developing Apple Mail plugins that now it is much more difficult (with Big Sur) and Apple added more restrictions. I assume MH is a plugin which, if it works as it should, goes deep into Apple Mail. Today it might be only possible with reduced functionality. I am not a developer, I just mention what I learned from a professional Apple Mail plugin developer. I think something similar was also mentioned here in this forum.
Today I use MsgFiler (with Big Sur) which allows me to file mails (but not automatically) or open selected mailboxes. Much faster and easier than with Apple Mail's own functionality (but of course not so comfortable as with MH). It is a compromise and better than waiting for a "Sign of Life" of MH for Big Sur/Anthony.
Of course it would be nice to read a (final) statement from Anthony about MH. But for me, no statement (for more than one year) is also a (clear) statement.