While I have a M2 Mini as my primary computer now, I held onto my 2017 Air as my travel / work computer - especially valuable as it was the last Air with built-in ports, and where not all locations have access to Wi-Fi or Wi-Fi enabled peripherals. And it still runs all the apps I need - some of them older versions, some current, and some that don't exist in Sonoma (it's on Monterey).
Now, I have noticed some sluggishness involved - some of that I put down to the difference in experience between it and the M2, but I also wonder if some of the subsequent patches Apple put out haven't helped? None of it is deal-breaker for the uses I have for it - while I also do my part in keeping it as clean and trim as possible - such as using the Maintenance tab in the free Onyx app. I also replaced the battery - for my own use, not because I believe it adversely affects the speed of the Air.
I may not be of the generation of your mom, but there's really nothing wrong with holding onto older tech if it still works for them - not you. Or Apple, who would encourage a new purchase (though if you do go that route, check out their Refurbished site in their online Store - buried in the fine print at the bottom of the page. Save some bucks and get an individually-tested device with full warranty - including access to AppleCare).