I realize I'm a hardware guy posting about a software company but I did make the switch to Salesforce's embedded/IoT platform team last year, so the onsite experience is real. Here's what I found.
Salesforce runs virtual onsites now as standard, at least for non-Bay Area candidates. It was Zoom with one interviewer per session, no panel rounds. My loop had four sessions over two days.
Session breakdown: Day 1: Coding (60 min) + Behavioral (45 min) Day 2: System Design (60 min) + Technical Domain (45 min)
Day one felt heavier because the coding round was first and I was anxious. By day two I'd relaxed. The spacing helped.
The technical domain session on day two was the most unique part. My interviewer was a senior engineer on the team I was applying to. He asked about real design patterns I'd use for event-driven systems with IoT devices publishing to a message broker at scale. It was clearly adapted to the actual work. I'd ask your recruiter ahead of time: what will the domain round cover? They usually tell you.
Logistics: they send calendar invites the day before. One 15-minute break built into the schedule between day-one sessions. No hard "interview lunch" which I preferred, since those are always a bit awkward.
Debrief took about a week after the onsite. My recruiter reached out on day 8 to set up a call. No email outcome, always a call, which at least told me the news was probably good. They would not confirm that but it felt like a tell.
Overall it was organized. Better than a few other big-tech loops I've done where the scheduling was chaotic and nobody knew what I was interviewing for.