The shaman king manga is basically out of print in my country. I still need the last 4 books to complete my collection (32 volumes). I understand Kodansha owns the rights to the manga now. With the 2021 anime coming out, has anyone heard about a physical manga rerelease? If they’re even doing that?

Honestly, I haven't heard any new news about a reprint happening for US audiences, and I actually doubt it will happen any time soon. I think the comixology deal is an exclusive. Maybe a UK or Australia reprint might happen but I don't have much network in that area.

Internet Lurker At Heart

I've had contact with Kodansha USA a while ago about Shaman King.
I only buy my Manga (when available in English) digitally from Apple Books, if available.
If not, then BOOK☆WALKER is my backup and then transfer it to Apple Books.

But back on-topic...
Kodansha USA promised me that the exclusive deal with ComiXology is only temporary.
They also assured me that the series will become available at other digital vendors and that a Print version is planned as well.

Although, nothing further is mentioned thus far, it's only a matter of time now.
So all we can do is wait for now...

Kodansha is doing an omnibus rerelease of the series