Asklemmy

Hard to pierce pseudonymity doesn't interest me that much, because it's bad enough having all your posts connected together.

I want something like 4chan (but heavily moderated), where all posts are just marked "Anonymous" and if you make 3 different comments, it's not publicly shown that they came from the same person. It's ok to retain the info privately for a short period, for moderation purposes. It could be ok to assign a persistent pseudonym for each thread, so if you comment 3 times in the same thread, those comments are connected to each other, but not to other comments in other threads.

This is a good article about the attractions of completely anonymous posting, though it's from the pre-supertoxic internet era: https://wakaba.c3.cx/shii/shiichan

My main concern would be usability. i2p usually has lag in the hundreds of milliseconds, which would make something full-featured like lemmy kind of a pain I think. I'd imagine it would be so slow

I would be too lazy to, unless I eventually encounter my 'gateway drug' to i2p.

How would it federate? Both in and out.

So, will it be a separate social network or a part of the Fediverse that will be able to communicate with the others?

Are people actually using I2P?

Everything will be allowed except for moderation regarding serious topics and spam.

So you're making a Nazi bar

You'd need to federate via a clearnet url, so you'd either need to not federate (so basically it would be a forum) or federation would just render it a normal instance that can also be reached on i2p.