operating system – How can i upgrade my raspberry pi OS to 64bit and keep my files and systemd services?

i have a raspberry pi 4 with an arm7vl OS, but i have to have 64bits OS to download geckodriver which i need, so i tried backing up my sd card on my mac using:

sudo gdd if=/dev/rdisk2 of=backup_4_10_23.dmg status=progress bs=32M

, then installing the new OS: Raspberry Pi OS (64-bit). After installing i restored my backup to the SD card so i thought i would have the new OS with my old files etc on it. But when i do uname -m on my rasp it still shows arm7vl. How could this happen and whats wrong? Does the backup restor overwrite the newly installed OS with the old OS?

So if i get it right, i can’t make a full backup of my current raspberry pi sd card(files, systemd services etc) then install the new OS on it and then restore the backup to it because it would overwrite the new OS with the old OS?

So is it possible to change the OS system to Raspberry Pi OS (64-bit) and to keep my files and systemd services with the new OS system.

I also want to keep my nginx service etc if thats possible so i don’t have to configure that again. The main reason for the update is so i can install geckodriver.