The only feature of Akkoma that I know about is their "Local Bubble" timeline which allows the admin to tag in the timelines of other instances to make a themed timeline, its a pretty nifty idea that should be brought into mainline Pleroma and Rebased.
Discussion
#[0] #[1] #[2] #[3] #[4] #[5] #[6] It already exists in Pleroma, just bloat is the only frontend that supports it. (Upstream bloat; FSE doesn't have it.) But the backend support isn't "bubble", it's just "Show this instance's timeline". In typical Akkoma fashion, the cool thing was crippled to "admin-approved instances because what if someone looks at a bad thing".