At least in that short statement, I have questions about both ideas. Having just vague concepts won't cut it here, because the UI is already pretty complex, so adding new features (and especially new data fields= requires some thougt.

1. I assume you mean national or personal holidays (as work-free weekdays are already possible). What would that information be fore, software-wise?
2. Story priority is (of course) modelled in the Product Backlog already, by the order of the Stories. What semantics would an additional priority field have?

I am currently looking at Kunagi and found this issue because I was searching for 'priorities' of user stories (I am not the one who created it).
For me, being able to give numbers as priorities for user stories is a must. For instance, if you enter 100 stories, handling priorities with number is much more convenient than putting them in the right order through drag and drop. That would be a nightmare. I see very well the 2 systems working together and complement each others.

About the holidays, it is useful for helping computing the sprint capacity, but I don't know if Kunagi already offer similar functionality.

What do you mean with "numbers as priorities"? Would you like to enter a number into a story field, which causes the story to move to the position determined by the number?

I see a problem with running such a system. If I understand you correctly, you want some kind of "bins" that group Stories of similar priority (determined by the priority field) together. Then you use drag and drop to give them priorities within the group.

Do I understand correctly?

I'd like to state that for all intends and purposes the priority has to be a total order.

There is a problem we run in when introducing such bins. I picture them as something like "basic" (must have), "linear" (the more the better) and "exciters" (nice to have). I don't see how else you would decide as a PO whether a Story is, say, a 3 or a 7. Such bins, however, do not represent priorities. In the end of the day, you will have mostly basic Stories at the top, and mostly exciters at the bottom of the Product Backlog, but this rule cannot be generalized.

We have some vague plans to make prioritization of big Product Backlogs easier (like iss76 and iss77), and maybe some improvements are needed UI-wise (which could be done in the context of sto117 and sto118), but introducing another property field for Stories doesn't seem to be the right way to go.

As for holidays, I would suggest to rely less on the tool and more on inter-personal communication for now. Maybe after we have completed sto175 (the new calender) and went on to integrate it better with the rest of the tool, something like personal holidays would be possible.