

Discord for me. A bunch of my family and friends are avid gamers. Discord is the universal standard app they all use for general communication.
Not only do they use it for all their gaming related stuff, they have additional servers and channels for just chilling, chatting, off topic stuff, memes, politics, etc etc.
It’s the network effect. Even if there was an open source app that perfectly replicated all the functionality of Discord and was just as simple to install and run as Discord, most of them still wouldn’t switch to it, because all of their friends and family are still on Discord.
So they would have to have two completely separate apps with totally separate social groups to maintain, and nobody but hardcore advocates for FOSS and privacy are willing to do that.
Sure, I have Discord, Matrix, IRC, Signal, XMPP clients, and a Private Mumble server, all on my systems, but I’m hardcore about FOSS. None of my friends and family are willing to do that. It took all my energy to convince two of my most techie friends just to get Signal on their phones. And only One has been willing to install a Matrix client to chat just with me.
well, I work in IT. So I am required to use apps like Teams for mobile and DUO 2FA in order to authenticate my laptop sessions.
Now, could I use only SMS/email 2FA? Technically yes. And I could just have Teams on my work laptop and have that nearby all the time, but it would be extremely inconvenient. Navigation would also be a big problem. Due to the nature of my job, I frequently have to visit a large number of different sites around my area. Having to open my laptop each time I need to go somewhere, open up a map site like OSM or Google maps to get the directions, print them off or write them down, then follow them manually hoping that I don’t encounter random slowdowns or closures in an area I am not familiar with is basically a non-starter for me.
As for personal use, navigation rears its ugly head again. I often will be traveling with friends or family and we decide on a whim to change our destination for dinner or hangouts after based on times, appetites, budgets, closures, etc. Having a map app on my phone makes that easy to do. It would be impossible to do that without it, unless I had a near exhaustive knowledge of my whole city and surrounding suburbs.
Honestly navigation is the #1 thing. Random other stuff comes up, like my mobile password manager Bitwarden, or my various apps like my City’s bus/metro app, and my city’s parking app. Both of which again, I could make do without, but it would be extremely tough and inconvenient.
I’ve decided that the happy medium for me is to use as much FOSS phone tech as possible. That way at least the tracking and data harvesting is minimized and I am generally not supporting megacorps.
I use GrapheneOS, with mostly FOSS apps. The proprietary apps I do use are isolated with GOS’s special sauce. I use Magic Earth for my navigation, which while not open source, the data sets they use are, and they are not google, and based in the EU, so far better privacy than Google’s trash.
I wish I could switch to a flip phone, I’ve seriously considered it many times over the last several years. But for my lifestyle, it’s just not feasible. The best balance for me is to compute ethically on my mobile. I have thought about going for the weekend with just a dumb phone, that might be possible, but I’ll have to see.