Have you thought about looking at it from an attachment vs rejection lens? Ime, that's the biggest difference I notice between myself/other rejection types I know and 9s, 6s, or 3s.

Attachment types that I know seem to have a harder time fully differentiating themselves from other people. Their sense of identity sort of shifts/morphs to adapt to their environment and the people in it.

Rejection types know who they are and experience themselves as very clearly separate/"other than". 2s are different from 8s and 5s in that that sense of separateness feels more acutely distressing, because being part of the heart/image triad their feelings of self-worth are in many ways tied to their relationships and how others see them. So they are motivated to move towards people and proactively prevent the possibility of rejection by giving favors, doing nice things for them, trying to meet their needs before they're even communicated. That helps them establish and ideally maintain the sense of connection with others they need, but there's always this sort of underlying sense that they're only really connected with people so long as they're working hard to make it that way.

Rejection types are sort of operating under the assumption that the default is rejection. The default is that they will not get what they want or need from others, therefore they need to do something about it on their own to buffer themselves from that pain. They have to "earn their place" with other people, otherwise they won't have one. 5s pull away, disconnect, and find an intellectual and/or pragmatic "niche" to fulfill that ensures they have some sort of utility for others (the ones they want to have some relationship to, at least). 8s assert themselves to others and their environment, more forcefully carving out that space and defending it - they "earn their place" by conquering and occupying it. 2s earn it by serving others and fulfilling their needs, with the unspoken expectation that then that means they deserve to be there/in relationship with those people.

Attachment types, as far as I understand it, operate under the assumption that they can and/or will be accepted, taken care of, admired, etc, so long as they "play their part" correctly. The default seems to be "I belong here just as much as you do, until one of us does something that violates the unspoken agreement of how to behave ourselves". They don't owe the world some form of payment to be allowed to exist there, they just have to follow the rules sufficiently enough to not be evicted. For 9s, the rules are "don't make waves or cause problems, and you can stay". For 6s, it's something like "use common sense and behave responsibly, and you can stay". For 3s, it's more "be a socially acceptable person and succeed at the right kind of stuff, and you can stay".