Okay, kind of an odd topic, but... I'm thinking of making potato spaetzle for a tuber-themed party this weekend. I have a recipe for spaetzle that calls for flour, egg, and milk. If I replace some of the flour with potato puree would it work? Or would it be just a pale imitation of gnocchi? Thanks for any advice.

I think that you would be making a gnocchi. Why not try to use potato flour? I am not sure if it would work, but if it does it will fit your requirements. If it works you could always try something akin to a baked potato Spaetzle, and add chopped chives to them, and then pan fry them in butter.

I tried making some pumpkin spaetzel with leftover pumpkin puree. Nice color, but had about zero pumpkin flavor. I used as much pumpkin as I could while still having a workable batter. I think pumpkin may be too mild to work as a flavoring in something like this (the squash gnocchi I've had don't taste much like squash either).

I'm thinkng that spaetzle are a delivery device for whatever you are serving them with. I've found that whatever I try to blend into the batter, I don't wind up with much of a flavor vector. You might do well with color, but only something that will impart a lot of flavor with a little quantity is likely to have much of an effect.