The company has the responsibilty to inform you but maybe not by call, but by email.

Supposedly, I was also 1 of 2 finalists. Fortunately it was only a recruiter phone screen and 2 rounds of panel interviews (1 phone and 1 video). That said, it's been exactly 1 month since I last heard from them.

It depends on the company. I once interviewed at a company (5 interviews) and was in the final two (I was informed), but not selected. Days, then weeks went by with no further contact.

Once in a while an interviewer called me but that was usually because we already had a professional relationship, we hit it off in general or made a good connection, but there ended up being a very specific reason another candidate ended up being selected and they wanted to explain. Sometimes they knew of another opportunity that might be a good fit. Most of the time I got a followup letter a couple of weeks later. One time I asked the interviewer why they chose a call or a letter. They said some candidates don't actually want a call...its awkward and they find it difficult not to react emotionally. They prefer a letter; less personal.

I hope things work out for you, but in 2020 it isn't uncommon for employers to simply ghost on job applicants. Don't get hung up about professional courtesy that they should phone you and explain the status and situation, because HR isn't evaluated on how they treat applicants. They are evaluated based on the number of offers accepted. And they know it won't matter if they ghost on you, next time there is a job posting they will still get tons of people applying.