Spouse had the interview recently (online). Very low-impact, no issues, agent quite nice. Started with routine question about whether any criminal or immigration issues that would prevent citizenship (to which answer given was 'not that I know of' - how should one answer that? Probably with a simple 'no.')
Checked we are in Canada now; asked to see (via webcam) ID and passports' bio-pages, about employment (general), clarified that frequent travel was mostly work-related, asked about a couple longer trips abroad (eg one vacation that resulted in a covid delay). Wasn't interested in too much detail, didn't want to look at the passport stamps or anything like that, declined offers of supporting docs (eg employment confirmation). Spouse had PCC (which we didn't submit because went by the application rules), also declined offer to provide (just said 'no need.') We have the impression the agent hadn't looked at the copies of all pages of passports we sent at their request (and to our great relief, did not ask for translations of the passport stamps).
Closed the interview by saying everything looks fine, security check still to be done, that could take a month or two, then the oath invitation. Nicely - given work travel - reminded that when oath is taken, would be without PR card and hence best to not plan travel between oath and passport issuance.
All of this was less than ten minutes, maybe closer to five. My spouse perhaps gave over-long answers to a question or two (nervous!), or tried to explain something that wasn't necessary/not of interest. Like at passport control, they basically just want the brief version of facts.
If I had to guess as what this was about (or 'for', if you prefer): just some simple check procedure for an application that had a lot of travel, 'gut check' that it's a real person who seems credible and that the basic explanations make sense, the background 'hangs together', something like that. Also clear the agent didn't want to spend a lot of time on the call - not rudely, just didn't think it was needed/other priorities.
We're going to try not to fixate on the security check timing or overall timeline (keep expectations low in other words).
[A small editadd later]: for explanation, my spouse applied with just over 1100 days, i.e. not much of a buffer, but we had very good records and the CBSA entry/exit records and were confident. But there was also one exit missing from the CBSA records, which hypothetically could have mean not enough days. We had other supporting docs to show the actual day of departure. So wasn't surprised they did an interview - although the interview didn't end up touching on that matter (although possible the officer had looked at those supporting docs and was just checking credibility as mentioned above).
