Sorta side question: is it legal/ethical to say, “open source unless you’re a company of more than X people then it’s X * $Y to license”

It's perfectly legal/ethical, but it would not be open source at that point. Same as licenses that prevent companies from running the licensed product as a cloud service, even if the source is freely available to view or use in a private capacity.

That's fine, except don't call it an "open source" license. That's a commercial license.

I think it's still open source, it's just not free right?

The Open Source Definition precludes that type of license, since it discriminates against Persons or Groups or Fields of Endeavor:

https://opensource.org/osd

You can of course create such a license, but it would not be an open source license, more like a shared source license or ethical license or something else.