that's correct, manjaro officially dropped armhf (you're correct, armhf covers armv7) support, but you can still use arch resources to do achieve your goal.
that walkthrough would likely work for your use case on a Debian build for the PBP, but if you install one, you might as well install the mrfixit Debian, which is already 32bit userland. Alternatively, if you want to try stay in Arch/Manjaro/aarch64, you could look into QEMU, too https://wiki.archlinux.org/title/QEMU its packages should be available in pamac under Manjaro. Another common method people have used, worked well to get armhf Chrome/Widevine, is to run the app from an armhf docker container.
that walkthrough would likely work for your use case on a Debian build for the PBP, but if you install one, you might as well install the mrfixit Debian, which is already 32bit userland. Alternatively, if you want to try stay in Arch/Manjaro/aarch64, you could look into QEMU, too https://wiki.archlinux.org/title/QEMU its packages should be available in pamac under Manjaro. Another common method people have used, worked well to get armhf Chrome/Widevine, is to run the app from an armhf docker container.