Here is Funko's POP Sonic keychain.
Annnd...it's not particularly cute. Sometimes the little Funko Pops are cute, like little funny Marvel characters or other video games where the people/whatevers aren't styleized . The problem with Sonic/and friends however, is that they are already very stylized and abstract to a degree, so doing that 'but more so' results in something super odd that you see here.
Sonic, fairly unique among cartoons has a single eye--which does not lend itself well to their 'blank soul-less dots on an expressionless face' gimmick. The single eye is a technicality but there's nothing doing for changing it.
The small body and actual spikes layout here is actually decent though. He's got a ring in one hand and finger-waving for his other hand which adds a little bit of dynamic/something new. You can see how nicely the head is structured around the spikes also. (Just too bad about the pop face)
The keychain itself looks to be a little large for actual utility. The ring is probably a standard size, meaning his head is a real whopper, and with spikes, it would make carrying it bulky/difficult.