Thanks!
Well, in my P1 there is a paragraph:
If you are outside Canada:
If you are currently outside Canada, you cannot be landed using the Permanent Resident
Portal (PR Confirmation). It is important that you let us know when you are planning on
returning to Canada by replying to this email. Further instructions will be sent to you.
So, they speak about some further instructions.
On the info
page about PR confirmation through the Portal they say:
1c. Confirm you’re in Canada
Declaring you’re in Canada does not mean you are a permanent resident yet.
We can’t confirm your PR status while you’re outside Canada. If you plan to travel before receiving your electronic confirmation of permanent residence (eCOPR), contact us using the email address on your invitation message.
And here it seems they also don't rule out the ability to leave the country.
Also, a piece of evidence from my personal case. My dependents also started as inland applicants with me. Then they didn't return after summer vacation. In response to P1 I just said they weren't in Canada and not gonna return before summer, so they submitted their documents to VAC abroad.