I can kind of answer some questions and throw my two cents in D
Extensions: Yes, you can use extensions - they are tied to the browser, not the OS. Tapermonkey is accessible on Safari, for example, as are many others. You can even repackage extensions for deployment in safari (or other browsers)
Stealth CORE: no (I think?), but you can maybe arrange that through VMs? I only know of VMware, don't use Stealth CORE and have no idea if that would actually work - just a guess, someone else will probably know more XD
Gaming: neither gaming laptops nor macs are really made for gaming, and a shorter lifespan on laptops is pretty much a given. A well-maintained system, of any kind, will last - you can trash a Mac too. But if all you're doing is neopetting then you aren't making major sacrifices there!
Misc - consider maintenance costs of owning a Mac. Depending on where you live, you may not have access to Apple-authorized repair partners, and in many cases third-party repairs will void the warranty. Even if you can repair the mac through official channels - expect to pay a pretty penny, sometimes as high as the cost of the mac itself. It's a great business model, really - make repairing a good product so difficult and ridiculously expensive that you might as well go and buy the new whatever-it-is.
I am biased against them, but there are pros to owning a mac too: using the OS is really straightforward, owning multiple apple devices is like a dream come true - everything is perfectly in tune with everything else, macOS is freeeee, the displays are to die for and the track pads are hella nice too. And, despite the cons of repairing one, it's just... easier. Whatever happens - you leave it at the Genius Bar, empty your bank account and pick it up in a few days like nothing happened.