The rest of my comment does explain the logic:

If a SaaS app is closed source, like this one appears to be, if it closes (e.g. if they're acquired, decide its not profitable enough, lose interest, etc) I have no options. Maybe I can get my data out, but then what?

If a SaaS app is open source, and the paid version is essentially paying for the service of it being hosted, I have no concerns: if they close for whatever reason, I can run (or pay someone to run) the open source software.

> If you do know anything that looks as good as Vectra please throw out a link.

I haven't tried it, but I'd imagine the recent(ish) browser-based LibreOffice Online might be usable for the same purpose?