This time of year given the Bolt's range you should really only need 1 full charge to accomplish that trip - it's only 590KM. Stops for lunch/shopping and such can be planned around L2 chargers as well and you could pickup a little there as well..and they're often free.
I just did a search on Plugshare and it looks like many of those chargers you're seeing listing EVGO as a payment option also accept credit cards directly, so I'd opt for that vs trying to sign up for an account you're not apt to use regularly, particularly since I see some of the EVGO plans carry early cancellation fees as well as monthly service fees, and the only one that doesn't is neither inexpensive, nor is it clear (as you mention) if Canadians can even sign up for it.
I just did a search on Plugshare and it looks like many of those chargers you're seeing listing EVGO as a payment option also accept credit cards directly, so I'd opt for that vs trying to sign up for an account you're not apt to use regularly, particularly since I see some of the EVGO plans carry early cancellation fees as well as monthly service fees, and the only one that doesn't is neither inexpensive, nor is it clear (as you mention) if Canadians can even sign up for it.