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And you have to 'activate' an iOS device with a SIM card. No such need for any android device.

Clearly not the case for Apple TV, which is the product being discussed here. See:

The only device that requires a SIM is an iPhone for obvious reasons.

And Apple is in the forefront of pushing for a integrated "SIM", effectively going back to the CDMA days...

Would this be similar to the eSIM in my Pixel 2 XL?

Yes