Having no WhatsApp, no Spotify, no banking app, no Apple Pay or NFC payments, no Widevine so no Netflix and so on is making using Linux on the phone very difficult for both Android and iOS users unless they REALLY want to
So until things improve and there are more alternatives to what you mentioned, this won't be a mainstream device. And that's fine. We should celebrate where we are today compared to a few years ago.
Well, mostly: You can use Spotify Premium, thanks to Spot: https://github.com/xou816/spot
(I could go into bridging WhatsApp over Matrix, or using WhatsApp Web, but I realize that that's most likely too painful for most. Also, Waydroid makes lots of things work, but the side-effects on battery life made it seem impractical to me, to be honest.)