It can't be done natively, in otherwords, there isn't an established method in the dashboard to achieve it. None that I'm aware of. However I would try reaching out to Roku in some way (mod: Roku Shawn or Joel or whoever the current one is). Or if you have any contacts or past emails you can reach out to.
Possibly it can be done on their back end, I'm not really sure either way of how much of a technical workaround it would be for them, (possibly it just can't) but you should get in touch & see if they can assist you in this. Makes sense what your asking, it's just the technical/backend of if they can do it. Hopefully they foresaw things like this when implementing the DP infrastructure & anticipated conversions like this.