The phoenixd server handles small first receives differently than mobile app Phoenix. The fee credit system might be interesting as a comparison, with the main caveat that small receives are only accumulated until they can be used to open a channel.
https://share.google/dRjeZArKO0HquEL0m

In Phoenix they solve the low value wallet problem with JIT/zero conf. I'm curious how Spark compares to that solution. Phoenixd also handles low sat payments with a custodial credit system so maybe that's the biggest difference. You can receive but not resend low values.