I’ve been getting regular nags to upgrade my Sonoma to Sequoia and I’m wondering if I should just bite the bullet and do it.
I’m perfectly happy with Sonoma – the only reason I would upgrade is to stay current with security updates and also not put myself so far behind that when I do eventually have to upgrade it’s a nightmare.
Other than making sure that my software will all be compatible with Sequoia, is there anything I should be concerned about/aware of before pushing the button?
I’d say as long as you have a trusted, recent backup of your data (ideally, backups) and you don’t rely on an application or utility that will stop working for a critical purpose, it usually makes sense to upgrade from an OS that no longer receive security updates.
As someone who keeps computers far longer than others (e.g. I still travel with my 2011 MacBook Air), I would say that the critical thing is that any Internet-facing software be kept up to date with the latest security patches.
This doesn’t have to be macOS itself if you don’t use any of its bundled Internet apps (e.g. Safari or Mail). I’m not very concerned about things that access Apple’s own servers (e.g. the App Store). I also have no problem with apps that don’t access the Internet (e.g. my Microsoft Office installation, which I never use with documents I didn’t create.)
Fortunately, Firefox ESR 115 (the last version compatible with macOS 10.12 Sierra) has been supported through September 2025, and since that’s the only Internet-facing app I use on this computer, I don’t have a problem continuing to use this computer.
Of course, if they don’t extend ESR beyond September, I’ll need a new computer in October 
. Fortunately, even the cheapest base model Air will be more than sufficient to replace that ancient system. Unfortunately, the least expensive model still costs $1000 (or $780 for a refurb). Hopefully, the Mozilla people will keep up the security updates for a lot longer 
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I sympathise with the annoyance from upgrade nags!
If Sonoma suits your needs, I’d suggest ignoring the nags (I’m not aware of a way to disable them) and sticking with Sonoma. ‘Right tool for the job’ concept. I still use a MBP with Sierra on it but only rarely connect it to the internet and it doesn’t leave the house or do other dodgy stuff that I’m aware of.
Joe Kissell’s ebook Take Control of Sequoia might have some info in the introductory section on differences between OS versions that would enlighten your decision.
I don’t necessarily worry about the security theater Apple and others play. They no longer give consumer-level useful information for making an informed decision of whether their fixes solve a threat the user would even encounter.
So imho I’d suggest focusing on what the key aspects of your computer use are and if they would be enhanced with features in Sequoia. If so, go for it and deal with the ‘nightmare’ and otherwise be safe and be happy.
“And one more thing”…I think it’s important to think about how you use your computer (personal, business, mixed), what you have stored on your computer (easily replicated personal files, client information, irreplaceable photos, etc), and, perhaps most importantly, the situations of those offering advice. For example, a long time hobbyist, a retired person, and somebody who is self-employed will all have different views on when it is best to upgrade.