Thanks to @silverpill, #Fedify is finally FEP-8b32 compliant! Though it's not ready for general release yet, it's passing tests in the latest main branch. I'll test it with Mitra and other FEP-8b32-compliant implementations, and if it works well, it'll be included in 0.10.0.
You can try it out in version 0.10.0-dev.205+0cbca257.