Blocking email by country with amavisd/postfix/spamassassin

Hi, I have a fedora32 server system with amavisd and postfix installed and would like to block all email from China and a number of other countries. It doesn't look like there's an easy way to do this. Perhaps a better approach would be to block all email and only allow connections from US servers (even though foreign email could be routed through a US server first)? Would the GeoIP stuff be helpful in amavisd? Perhaps we can block by ASN? I'm also using spamassassin and could write rules to block email based on the TLD, like .cn etc. Perhaps we could create a policy bank or domain map with a list of the different countries? Maybe a sender map that can block on a per-recipient basis? I've done quite a bit of searching and most of what I see is from decades ago to links that no longer exist. Thanks, Alex