Tomato firmware has an option of "no qos ingress for udp" which makes sense that udp doesn't rely on feedback to slow down or adjust it's rate. Is there a way to implement this in OpenWRT?
That is not correct in general, all flows over the internet are supposed/required to avoid congestion collapses and are suppoosed to be TCP-friendly which translates into "should respond to congestion signals like drops and optionally CE marks by reducing their send window/rate". Not all do that though, but for example bit-torrents µTP protocol uses UDP but responds to signal. In theory you could configure create a new script that uses HTB or HFSC and steer all incoming UDP into a specific leaf and there use an fq_codel or cake instance with an exceptionally long interval and target setting (which essentially makes drops/marking very improbable). My intuition is that this is not going to help much, and if it does it reakly points out a UDP application that is not compliant with the IETF's RFCs. The potential exception would be UDP based constant bit rate real-time streaming IPTV kind of traffic, and that should ideally be separated from other best effort traffic anyway to guarantee the required bandwidth.
But that is just my opinion and could well be wrong.
the SQM packages used by openwrt are not actually part of the project
open an issue there if you want