Hello,
I am currently in a similar position but with RPi3B+, running Bullseye 32bit.
After scavenging the forums I am under the impression that 32bit → 64bit transition is possible but with potentially a destructive operation, which requires manual bootloader update: Update from bullseye 32bit to trixie 64bit? - #2 by TheYoctoJester
However, I myself am now stuck with transition from bullseye 32bit to bookworm 32bit. Would you be kind enough to share some of your progress on the transition?
Kind regards,
Dmitrij