Last I checked (roughly 2 years ago, preRAM price spike) SBCs weren’t the most cost effective option for self hosting anymore. I would actually look into used thin clients or desktops. Even new, the hardware is often less expensive and more capable than SBCs. Sometimes they’re also more power efficient.

As for community support for the SBCs other than RPi, for most of them it has been close to non existent. Some better than others but the RPi was the community favorite and got all the attention due to its low price at the time.