for the sake of this question i'm gonna ignore the current canon ships (kirisakis, mahiru and her bf, and kazuhina) because i assume this isn't about that sorta stuff

before i start i wanna say this isn't reflective of what i personally ship and is solely an analysis of relationships in the series! if you wanna know abt what i personally ship that's another thing entirely, this is just what i think could reasonably happen

i think the absolute closest we'll get to canonical ships is 0104 and something akin to that, honestly? i don't think there will ever be a healthy or even explicitly romantic relationship in milgram for a variety of reasons, but the main reason is that i don't think a healthy romantic relationship would be narratively interesting (or possible in a lot of cases) for any of them?

i could see them doing something with mahiru and shidou, to the effect of "omg he's like my knight in shining armor... he saved me... swoon!!!" shidou will 100% NOT like her back in that way, but i could see him growing closer to her. i think it would make for a very interesting dynamic between them! but i don't think it'll ever be like. a good healthy relationship / dating.

as for other prisoners, i think 0104 and 0909 are the closest we're getting (despite neither being explicitly romantic), and both of those are deeeeeeply unhealthy relationships for one reason or another. and tbh that's how i like it! i love seeing unhealthy, fucked up relationships in media, and i hope to see more of it in t3!

i do think between prisoners the most likely to get into a new relationship are mahiru and shidou like i said before, but for the rest i just don't see it working based off MY reading of the characters and predictions for their character arcs. friendships, maybe! but anything even slightly leaning romantic..? nah. i just don't see it happening in canon at the moment.

as for outside of milgram, i really only see like... MAYBE muu being in love with rei, but it's clearly not reciprocated, so i wouldn't call it a canon ship. past that i literally cannot think of any shippable side characters so. nah. nothin there either.

tldr: i don't think any ship will ever be canon in the way the fandom does shipping, but i could see mahiru and shidou getting into a weird kinda relationship after both their inno votes. won't be healthy, though. i don't think any "canon ship" will ever be healthy, really, just by nature of how the media is, and i love it. i love a good unhealthy relationship in my media.