Interesting.
In any case, it's a logical partnership. He's the right age--not so young that this would mean forfeiting an Olympics or two. He has experience--he's been to Europeans, the Olympics, events on the GP, and won German Nationals. He's competed at the senior level since 2015-16. I think he was the stronger skater within his previous partnership. (Better edges). There will be the whole challenge of starting over for both of them, but as new partnerships go, this one seems plausible.
We'll see what happens with the citizenship challenge. Perhaps there would be better support for them if they skate for Germany. Or perhaps it would not be so easy for an athlete to get citizenship in Spain via a partner who obtained her own citizenship via skating with someone else. Or perhaps the release timetables are different. There are a lot of aspects to the challenge. It's become more difficult during recent years for athletes to obtain German citizenship than it used to be, but not impossible. At any rate, these two have enough options, I'd think they will find a workable pathway.