My primary use of the late 2015 iMac is for web browsing, listening to playlists on Apple Music, to which I have a subscription, and occasional photo editing using the native macOS application.
Nothing else. No professional programs like Photoshop or others. I hope to be able to install Tahoe so I can continue using only native Apple applications (Safari, Photos, Apple Music) for a few more years with the security of an up-to-date system.
And when Safari is out of date, I'll stick with Firefox ESR for a few more years. I can't bear to abandon a product that still serves my needs perfectly, even though it's 10 years old.