Egi, egi... how about attuning to the dead?

[Shougun]

I don't see anything wrong in the sense of having them 'look' like those people you mentioned- in mechanics of the game's lore, it's just clay lol. Summoners being baby gods and all. Few would know hade's appearance so it would likely not cause too much issue if you imagined being an NPC in the game, of course if you use a dead NPC's image that other NPCs actually know then they might accuse you use of necromancy though (even though it's not). There is the whole limit on attunements and such but I think that is easily irrelevant as we become more whole (we are abnormally aether dense, the rules that other normal npcs have to tip toe around can easily be waived off on this logic alone).

Having them be the actual person raised dead version of them would be a monumental hurdle to clear though lol.

As for just their spirit, with the advent of soul magic, I think you might get something akin to a 'good' Necromancer (a person who communes with the dead/otherworld)- just don't raise their rotting flesh and force Y'shtola's grandma to fight.

There are still a number of hurdles to worry about, but if one was driven enough I'm fairly confident you could navigate over around and through them (like not raising human zombies, phrasing any situation of humanoid souls as 100% voluntary, being very cognizant of art direction implying certain concepts (no human zombies), etc).

In a semi-convoluted way you can think of it like our soul crystals with some of the crystals passing knowledge to you to use through them, this is very very 'light' form of necromancy as the aether of past people is stored in the form of knowledge that you can access. The game I doubt would ever phrase it that way, but so long as you mark "commune with the dead" part of the definition some of the soul crystals are this way. (I say some since some are new / made, but a few when you do quests will note about the past deeds and knowledge stored in the crystal). IIRC White Mage's soul crystal literally states a soul is inside it.

Necromancer isn't my one true love job or anything but I tend to see people being way too strict on a fairly loose concept of what is and isn't allowed in FFXIV. There are multiple occasions when we've interacted with spirits in some way or form that wasn't bad. It really isn't that big of a leap to suggest you might be able to coax a soul to do what you would like without corrupting it, given the proper knowledge (as there are many examples where this has absolutely gone wrong, and of course the vast majority of people we know that work with souls have been evil, but so too in other magic fields can you have devastating problems like in White Mages and Black Mages). Which eeeehhhhyy we have a soul magician in our a game now, so it's a potential more so now than ever.

Generally speaking on my personal desires I think Hades content for summoner could be interesting, but I'd avoid any normal things for Summoner. If you were going to do soul magic that isn't connecting to these grand creatures I don't think it should associate with Summoner.