They still have webkit builds for Windows and Linux etc, and you still don't need to buy anything special to run it. I think they also have a (mostly?) headless one, and a mini-browser which is intended to test the engine (so it doesn't have things like bookmarks or profiles or anything like that, a good fit). Similar options exist for FireFox and Chromium so it's not really a Safari/Webkit special. Usually gets used when you use a standard containerised browser testing CI step.

Either way, if someone is still manually testing their website instead of using a standard automated testing system you're probably not really in a league where this matters anyway.. and if they are, you probably have a device farm already.

Not sure where the "my thing is so important, I have to test it on a real device, but I can't pay for it" niche is.