It's a little hard to do a direct comparison, because I think the creators have purposely shuffled things in order to not be seen as repeating themselves. That said, it seems clear that there has been a conscious effort to find the things from Frontier that worked so well and generated such a huge new audience while trying to fix some things that didn't work so well.
From that standpoint, while I don't think any of the characters map one to one, I do see:
Hayate = Alto, but less mopey (I see more Hikaru here than Shin, though, as he doesn't seem angry at all, unlike Shin or even Alto for that matter)
Freyja = Ranka, but with more agency and self motivation, cute but no longer moe
Mirage = Sheryl, but with less ego and more self doubt, almost Sheryl + Alto in a way - strong, self determined, but with something to prove
For the rest, it's a bit early to say because we haven't had deep exposure to too many yet, but clearly having a strong ensemble was one of Frontier's selling points and they're trying to bring that about in Delta as well. I expect each of the characters to be given a chance to shine as we go forward and add dimension to themselves. Like Messer enjoying the kids in the OP and the Captain being clearly depicted despite having had almost no lines so far.