Frosty looks into the Iterate node in Bifrost and covers feedback ports and appending arrays.
The Maya Bifrost Iterate Node is similar to the For Each node. The difference is that the Iterate Node is sequential while the For Each Node is a parallel one.
That function alone means that the Iterate Node will allow you to use feedback ports and append to arrays based on a condition.
This new tutorial from Youtuber “Frosty” shows how to set up feedback ports inside of an iterate node and append to arrays based on a condition.