I initially used the class-10 microSD card that boots the Pi, but I've moved to an ISCSI mount on my NAS, mostly because I have an unsophisticated LFS setup
Remarkably, Gitea can also run directly on my NAS with it's very slow CPU and limited memory. I wouldn't be surprised if it runs on other "appliance"-type devices like routers & NAS with 10+ year-old ARM or MIPS microprocessors.