Personally I do take at least a quick look over sources before deciding to trust any new app. I simply won't install apps that don't provide the option.This used to be an ideological stance but increasingly recently it's the only pragmatic thing to do from a stance of security and safety. The playing field is increasingly hostile and if someone asks you to install their software on you machine and let it record your face and voice but refuse to show what it actually does, that is a red flag. Reasonable exceptions could include video games (which run on dedicated untrusted devices and IMO the IP aspect makes the closed-source stance more understandable there). On the other hand, this app is inherently sensitive and trusted because of its function. I don't see the reason why it needs to be closed-source.
Malware is commonly distrubuted in all app stores. I reported some obviously pretty bad stuff that is still up a year later on Play Store, for example. Google simply doesnt bother if the case is too messy.
> hmm not sure yet on the open source thing
You could start with just go source-available by sharing the source with your users without going full Open Source, if you want to take the time and think about what license to use.