I'm sure this is a very common post but please hear me out, I'm in a weird place and don't want to make a poor decision when it comes to such a big purchase, let alone potentially three of them.

Until very recently, I was under the impression that Linux phones weren't a thing. Had I known, I likely would have made this post several months ago and bought a different device for myself (I'm using a crazy overpriced Pixel bc I thought GraphineOS was the ONLY option for a safe and FOSS phone).
I have two partners in the US who's Androids are old and even falling apart on them. They can't afford one Pixel, let alone two, but I've gotten them into Linux Mint and want to take this opportunity to rid their phones of proprietary software as well. So here's the deal:

I have little to no knowledge of Linux phones. I don't know if they have dedicated apps, or if all software is run through Android emulation, or even how different Android is from Linux itself (isn't the former based on the latter anyway?). None of us need high-spec devices, we just want something that can:

• Play media files and use privacy respecting YouTube clients, stuff like that
• Send and receive texts/calls through Signal, Telegram, etc.
• Actually deliver notifications (GraphineOS is horrible for this in my experience)
• Use your average social media (Mastodon, Bluesky)
• Has expandable storage and preferably a headphone jack
• Isn't total overkill and won't cost a grand for useless features and specs

I don't expect any phone to fit the bill perfectly, but if you guys know which device and OS I should try, I'm all ears.
Speaking of operating systems, I'll go looking around this community to try and find some individual pros and cons, but if anyone has experiences to share, please, please do.
My plan is to find which pairing of device and OS is easiest to operate with the least drawbacks and get used to it myself. Being the techie of the trio, I wanna be able to help them if something goes wrong. Once we've made a decision, I'll buy and set up another phone, then send them both to my partners so they can finally have new phones that are FLOSS, free of corporate spyware, and hopefully last them a good while.