My thinking is that aliens ‘observing us’ would probably be extragalactic in origin.

If they aren’t, that implies at least two sets of civilizations arose in the same galaxy, which implies a whole lot more are out there and kinda twists the Fermi Paradox. See:

One great mystery has puzzled thinkers for millenia, a mystery which first became apparent even before the first space flight. If intelligent life existed anywhere else in our Galaxy, why had it not colonised the earth long ago? This question was first posed by the classical age physicist Enrico Fermi, but was refined a few years later by Frank Tipler, who realised that if any intelligent species developed self-replicating probes, then it could explore and ultimately colonise the galaxy in a few tens of millions of years. But this had not happened.

https://www.orionsarm.com/eg-article/47faddfe17122

The Ginnungagap Theory was advanced to explain why the entire universe has not been converted to a single technosphere by the earliest intelligent beings or any of their successors.

https://www.orionsarm.com/eg-article/464e942db2789