Edit: I noticed your other post about PNP nomination. My post is general information for Spousal sponsorship only. I don't know much about PNP. Hopefully, it will still be helpful to you. I'm going to leave it up as it might.
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If you want an open work permit, you need to file an Inland application.
First, your husband need to come back to Canada. If he's a US Citizen, that shouldn't be that difficult. (If you're concerned, search the search feature and try keywords like "American visiting Canada.")
Second, you can file the Inland application once he is inside Canada. It's not recommended he leave Canada while the application is in process. If he leaves and is denied re-entry for any reason, this application will be considered abandoned. It's unlikely an American would be denied entry, but anything can happen. If he knows he has events he needs to attend in the USA (weddings, family gatherings) make sure you consider this.
Good news - if he legally enters Canada on his passport stamp, the Inland application will automatically give him "implied status" until a decision is reached. This means he doesn't need to leave Canada to maintain his visitor status.
For fastest processing, include the OWP application with the PR application and pay the OWP fee with the other fees.
It takes 6-7 months to get the OWP. He needs to remain in Canada for this (except short visits, but see above warning about that). He cannot sit in the USA and work and expect Vegreville to consider him an Inland candidate (if they find out).
If you do an Outland application (he can travel freely without worry about abandonment and work in the USA) he will not be allowed a OWP. However, he can work, which he won't be able to do until he gets the OWP or finds an employer willing to provide a LMO for a closed work permit.
Inland takes about 14 months. Outland is showing 12 months, although faster times are regularly being reported.