Maybe also have a look at my https://www.pipes.digital/ if you want that :) Filtering and merging RSS feeds is the main use case, and I made sure to have some features to enable building on top of other pipes (a prominent fork button for shared pipes and a pipe block).
Great stuff :) That's exactly what I meant :thumbsup:
I actually found www.pipes.digital in my mind map with a comment to the effect that it's a Yahoo! pipes replacement - so I come across it a year ago in fact.
I'm sticking to Node-RED simply because that's what I know - also its open source and very extendable, so that's why its my cup of tea.
EDIT: Pipes is also open source --> https://github.com/pipes-digital/pipes --> sorry didn't see that.
Great that you found the Foss version :) I hesitated there because it needs an update, and node-red is great and easier to extended. So if you are already familiar with it a great choice.