What about FOSS SaaS alternatives that are meant for team collab? Like Plane (Jira replacement). Does that have to be ran locally at home for it to be considered "self hosted"?

Self hosted means you host it yourself. I.e. you run the software. Running on your own home machine is definitely self-hosted. Hosting it on a VPS in some datacenter still is. Running it in a cloud platform somewhere is stretching it but I'd say that sill is. SaaS definitely is not self hosting even if the software is open source. The important part is that you're the one in control of the software.