Given the current situation with Zoom, it may help increase trust on HN if you can add information about if you use E2E encryption and delays and location of servers and if its a centralized or de-centralized architecture etc.,
Looks like the feature set perfectly fits the usecase for remote teams, but using something along side Slack like apps, people may feel the friction since Slack itself consumes too much memory among other things. Going around multiple apps itself is a pain. I see that you have them linked through Slack apps.
As an alternative, I personally feel Discord to be a Slack's better version. Discord is used by mainly by gamers around the globe to voice chat during online games. Discord has Pragli + Slack combined - threaded conversations.