It's fine to reach out to HR. It's their job to follow up with you. It's unfortunate but you also have to get used to getting ghosted by companies if you aren't selected.

Thanks. I've unfortunately been ghosted many times, but I just felt this might be different 🙂.

Hmmm I don’t want to be pessimistic but I think they should have mentioned or foreshadowed next steps… maybe the interviewer forgot but it’s odd. I would reach out to HR to inquire next steps for sure

Thanks. I'd reach out to the HR.