I would say no, and I would expect any sensible country to bar this within its borders. To the extent that a state should have a nonviolent means of secession, this above all should not be subject to foreign interference.
You can find a more detailed view of my opinion on specific independence movements elsewhere in this thread.
Regarding California or indeed any other state breaking away from the US, it's none of our business. And, before you ask, in the highly unlikely event that they wished to join Canada, I would expect them to gain independence and then, separately, start any process of joining another country.
She's an anti-vax, convoy supporter who wanted to withdraw Canada from UN and UN-affiliated groups like the WHO. She famously hosted Christine Anderson from the AfD. She is stridently anti abortion and social conservative, and strongly pro-Israel.
I don't see why she would be better than Poilievre, it seems she would somehow be worse. At least Poilievre condemned the AfD meeting at the time.
I suspect that she is rather strongly allied with the religious right in the US, and therefore she would be even more likely to suck Trump's nuts from the back. I don't see indication that she has any national pride or vision that unifies Canada. And I've never heard anything interesting from her on economics, which is arguably our most important file right now.
MAJOR EDIT NEEDED: I'm a moron who thought the Lewis under discussion was Leslyn Lewis, instead of Avi Lewis. I have no excuse. The above was not meant to apply to Avi Lewis. Please downvote and ignore. I don't know anything about Avi Lewis.