Unless they're very lax about what constitutes multi homed I meet zero of those requirements.

Does me renting a server in a DC count as multi homing? Bridging my network to my friend's place over wireguard? Doubtful tbh

Typically, multi-homing means having an ASN and using BGP, or having multiple providers with BGP announce your prefix. So, a server in a DC might count, if you can get them to announce your prefix, though they'll probably want to announce their own prefix and give you a chunk of it. Your home network probably isn't going to be announcing your prefix.

It really depends on what you're trying to achieve by having a direct IPv6 allocation...

Maybe I just want a /48 or something, to do whatever with.

If, as ARIN claims, ipv6 scarcity is not an issue then it's very frustrating to deny me the ability to get my own chunk of space for my own purposes.

It shouldn't matter what I plan to do with it.

I hear what you're saying but if you aren't going to publicly route those IPs, ARIN has allocated fd00::/8 for that use. If you are going to publicly route your IPs, ARIN has no problem allocating you the space.