Linux
I recently picked up a 2014 MacBookAir in a market for 50 quid to try out Linux on. With the Big Sur Os it was arthritic and could even run Chrome browser. After a bit of tinkering I managed to install Linux Mint and have been amazed by the performance, the latest versions of what I want to use or the equivalent are readily available and except for some slight hesitation when trying to do several things at once I can't tell that I'm using a twelve year old system. Apart from not being able to get the WiFi to work which meant ordering a USB plug in device there have been no major issues. With Apple quality, even the battery still works okay, though I wouldn't expect a full day's use out of it. Replacement ones are available online for a reasonable price, and fitting is a DIY job on this model. You can even get a USB C to MagSafe adapter which does away with the need for the proprietary power supply.
This will be my travelling laptop and I'll get something a bit more powerful for home use, such as a Lenovo Thinkpad T14 around 4-5 years old and also install Linux on it. I'm now officially off the upgrade treadmill and look forward to cheap second hand hardware, free open source programs and not having to subscribe to anti-virus software.