If “they” really do exist, you are mostly correct that they wouldn’t be interested in us..
Of course your ETH aliens, if they are even 1000 years more advanced than us would have the same issue.
I’d say that the most relevant answer in terms of the PSHP would be that it is “us” which are sometimes materializing things…then going “Look! Look! I see a puddy tatt! Er…nuts and bolts ETH alien”.
Thus my comment about UFOs going away once we all grow up and stop materializing them….and gods…angels..demons…poltergeists…etc.
Now one final note.
Even 10 billion year old (very bored) AI might find it intetesting to watch the second ever species (some low number) in the Universe to make it post singularity.
Then perhaps swallow us up into their culture…but who knows…they might let us settle our galaxy before confessing their full presence.