I'm not an expert by any means but as far as sequential recommendations go, aren't SASRec and its derivatives pretty much the name of the game? I probably should have looked into HSTUs more. Also this / sparse transformers in general: https://arxiv.org/pdf/2212.04120
There's a few alternatives, but SASRec is a good baseline for next-item recommendation. I'd look at BERT4Rec too. HSTU is definitely a strong step forward, but stays in the domain of ID models. HSTU also seems to rely heavily on some extra item information that SASRec does not (timestamps).
Other models include Google's TIGER model which uses a VAE to encode more information about items. Similar to how modern text-to-voice operates.
Thank you for the recommendations. I didn't try BERT4Rec because I assumed it would perform the same or worse as what I already had after having read https://dl.acm.org/doi/pdf/10.1145/3699521. The TIGER paper seems interesting - I definitely want to explore semantic IDs in general and also because I think it could allow including more long-tail items.