Is privacy compromised when using privacy-respecting apps on non-private operating systems?

Well I guess if iOS or windows etc. can access keystrokes or text when an app like Signal or Threema is open then it’s not nearly as secure and private as everyone claims it is?

And I’ll be changing as soon as I can receive my L14! :grin:
As far as an open source software phone the L5 is still a year or more away for me and I’m beginning to look for alternatives.