Currently, I don't use a banking app because I don't trust my bank to have that level of access to my phone with a proprietary app, and because my bank's app isn't particularly good in the first place. So I'm not really losing out by using Pinephone. In fact, I might have more functionality after switching, since Android development is a mess and on a Linux platform I might be tempted to build something quickly for myself that periodically pulls down the CSV data from my bank and does a few things with it.
I'm not saying that proprietary devs are going to start mass-building apps for this, I'm just saying that for a segment of the population, this may turn out not to be the problem you think it is.
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Apps on my phone that I need replacements for:
- NewPipe
- Podcast app/music app
- Maps
- AndOTP
- Signal (and/or Matrix)
- Orgzly
- Good browser support
- Maybe a few misc utilities, probably something I'm forgetting
Do I have confidence that those apps or equivalents will be ported? Honestly, yes, I do. It would not take an insurmountable amount of work to build a Linux ecosystem that was more functional than my current phone setup.