Right, human technology can detect up to hundreds of light years[1], but presumably advanced alien technology can go further. See for example[2]. Hard to say how far.
that is next to nothing, observable universe is 93 billion light-years
around 0.1 stars per cubic light-year (Google response)
universe is humongous and very very sparse, our current limit is light speed.
> advanced alien technology
that goes against my second claim, lol, they (if they exist) are capable of observing and understanding us, we can't observe them and, quite likely, we are unable to understand them.
every other civ that is as primitive as we are is bound by the same light speed constraint
[1] https://www.nasa.gov/universe/exoplanets/webb-discovers-meth...
[2] https://www.youtube.com/watch?v=4d0EGIt1SPc