Have to say he was not on my radar but I don't feel like it would be a bad choice at all. We absolutely need another right back option and one that allows us to play the same way if Nunes is unavailable. Most of our big losses earlier this year (united, bodo, madrid) came when Nunes wasn't playing.
Porro feels very similar to Nunes and will provide genuine competition for the spot, which is always good. Defensively question marks but not sure there's any options that wouldn't either.
Also, see a lot of people suggesting Nunes should/will be moving back into midfield. I don't get that. He's progressed amazingly at right back this last season and a half but I've seen nothing to suggest he's all of a sudden got the awareness, intelligence and consistency under pressure to play midfield to the level we're aspiring for