I think if you're planning on writing it then I (personally) wouldn't interact because it's too easy to de-anon yourself preemptively.

If you're going to request it too, or would eventually be interested in reading the fic that is produced (this would probably be a great thing for a Good Egg* to do, to let any potential authors know it's not really a fandom of two) but won't be offering/requesting, then commenting can't do anything but help, I think.

* the only downside being that if they think you, the Good Egg, may write it and are therefore intimidated and decide not to write it...