It has some kind of equivalent from my understanding. MP3 has frames https://en.wikipedia.org/wiki/MP3#File_structure and I'd assume all methods do, otherwise how could you start decompression if you don't have a starting point?

MP3 frames are all full frames, whereas a key frame is a full frame that is followed by incremental updates.

The prediction gain of audio codecs is <1, which basically means that if you start at a random packet, once you play enough packets it'll converge to sound the same as if you had started playing from the beginning. It'll sound bad at the beginning though, so you usually crop off the first bit after seeking (80ms for Opus, much longer for other codecs).

Another source of delay is just the length of audio packets themselves (have to wait for the beginning of one) and radio limitations.