Also, given that it's not open source, I can't trust it with my private Slack teams. I would seriously consider making the source open. You can still charge for it (and I'd love to pay for it!), but I need assurance that it's not doing anything untoward. Perhaps a Patreon level that includes source code access?
Having the source but not building it yourself doesn't rule out that the compiled app actually has different source than the code you got. So having the source but having it rely on some complex or irreproducible build system is not enough for open source here.
Also, given that it's not open source, I can't trust it with my private Slack teams. I would seriously consider making the source open. You can still charge for it (and I'd love to pay for it!), but I need assurance that it's not doing anything untoward. Perhaps a Patreon level that includes source code access?