I maintain an open source push notification service called ntfy [1]. It's 100% open source, but I have recently started offering ntfy Pro, a paid SaaS offering.

I am telling you it's super hard to get people to pay for it. It may be because the free tier is too generous, or because I don't aggressively push or market it, but most likely it's because people can just selfhost it. I have 25k active daily users for the free tier, and probably hundreds or thousands of selfhosted installations, yet as of today, I have only 20 paying subscribers. It's quite brutal.

The worst part is that ever since I started offering paid subscriptions, donations have reduced and new donations have pretty much stopped, because people think I'm making bank with the paid stuff.

I know this doesn't answer your question, but it gives you the perspective you may be actually seeking. It's definitely hard to pull off.

[1] https://ntfy.sh/