Google doesn't limit who can login by their device manufacturer, but the supposed privacy focused company does?

Yep, the privacy focused company makes money selling hardware rather than ads.

So, the privacy draw is just another gimmick to them, and not a supposed part of their DNA?

If you're not paying them, they need to pay for you to use their services. And to do that, they will want to make their money back on that.

It is a good thing that they're not giving their services away for free; they're putting their money where their mouth is. If you look at all the companies that give their stuff away for free, they do it to collect data for advertising, and they make money from advertising, in most cases (unless they're using investor money to fund you).

Apple is not an advertising company, and I do not see any problem in them using this to draw in customers. It is a major selling point for Apple that they respect your privacy. They do a lot of their ML stuff on-device to preserve your privacy, they encrypt your data on their servers or anonymise it whenever possible, they do a lot to prevent apps from tracking you like limiting location access and other data, etc.