Are there no tags for those consoles? Tagging the chip is not in use. It could be. But if no one tags x86, why should they tag AArch64.
A popular (non retro) console is playdate. There are 700 games tagged with that
https://itch.io/games/tag-playdate
While platform is different from a tag, filtering for AArch64 is useless, if no one else uses this tag.
Maybe try to find out, what other developers use as a tag for such content. Maybe retro or 16 bit or something like that.