* but I have to admit that the hardware is quite slow
It is because computers run one of a few available OS's. The OS is being maintained by the distributer (MS, Apple, Google) and your hardware is good as long as the drivers are still receiving updates.
Phones are different because even though everyone only uses iOS or Android, every Android manufacturer puts their own layer onto Android, so Google can continusously update it but the manufacturer might not. Most companies only maintain their phones for about 3 years, giving a significantly reduced lifetime than computers.
It still works fine, from from a security perspective, keeping the phone without patch support is a bad idea.
It is really annoying how every vendor cobbles together a Frankenstein abomination of a kernel with just the right drivers and patches and good luck trying to run anything else. But I also understand that they (except maybe for Google) have no interest or incentive to clean up this mess.
Fairphone 5 will receive security updates for 8 years
Pixel 8 will receive updates for 7 years
iPhone 15 will receive updates for 6+ years (apparently, Apple has a track record of between 6 and 8 years)
My laptop is also from more than a decade ago, and I'm happily running LMDE 6 on it.
Everyone doesn't have to live like this, but it's utterly valid, and no one has any right or justification to try to tell anyone else not to.
I can buy anything any time, but I miss swappable batteries, headphone jack, sd card. These were all basic utility features than made a device interoperable and more generally functional. Removing them only benefits the people selling new phones, wireless headphones, and cloud storage.
My old vaio 3 laptops ago is actually still perfectly fast enough at what I do today, it just only has usb2 ports, which eventually became too big of a pain point. But it also had a real docking station that you plop the machine into, not the stupid "docks" we have today that are not docks but just mega-dongle-hubs where you connect a usbc cable. I miss that dock every day since 5 years ago. I could easily still be using it today even though it must be 15 years old or more by now. And if I were, no one else would have any justification for trying to say that I shouldn't, and no software or service provider would have any justification for artificially creating some incompatibility that only serves their goals instead of mine.