Trunked DMR have priority option for TGs but not on one frequency systems which have the priority greyed out on the main page and are not visible at all in the edit system page.
One frequency systems normally have one slot for controldata and one for voice, no need for priority, and there are Hytera XPT channels that can have voice conversations on both slots, but it might not be a feature worth the hassle to develope only for those channels.
/Ubbe