What to do with ignored PRs?

[felixdoerre]

Hello, I would like to ask for some advice on how to handle Pull Requests that go ignored for a long time.
I realize that the number of pull requests on this project is high and reviewing or reacting on each individual one takes considerable amount of time, but on the other hand, having pull-requests sit around feels really discouraging and demotivating for the people who wrote them.
Especially if PRs are just a first step, it would be great to have some feedback if this direction is considered valuable or not.

While with issues others can try to help investigate/react/solve them, the same is not true for PRs as the number of people allowed (or responsible) for merging them seems very limited.

So the question is: How do I handle old PRs without any reaction, that are still, even after a year, important to me? Just Pinging people feels rude, but I am not sure what else to do.

This is probably related to #10317, but I'm looking for more concrete advice on what to do to make PRs more appealing so they get at least some reaction. (Even a "this is a good idea" from someone who could merge, without merging is still valuable feedback)