My husband just deployed and likes to pop in and see what’s up with the kids (usually just stares at the empty room, poor guy).
I want to set up two-factor authentication, but don’t want to lock him out. He’s set up on his device, and he has access normally. He’d have to have a code, correct? Even though he’s been invited by me to share the feed?
Sorry if this is rambling. I type how I talk in my head. It can become unintelligible sometimes. 
I just tried it on my wife’s phone which is a shared account and she has 2-factor enabled. I logged her off and when I logged her back in, she got the test for 2-factor. The problem you husband may have is if he would be able to get the text code where he is. If he can get the text from Wyze, he should be okay.
I should add that 2-factor, I believe is per account, so if he has his own login, then your 2-factor shouldn’t effect his.
The 2FA challenge is based on the account, not the camera. So if you each have your own account and you have shared the camera to his, you can have 2FA on your account and not have it on his if that’s what you need. As a shared camera, he will have less control over it than you, the camera owner, in case someone were to hack into his non-2FA account. As always, be sure you both are using strong passwords that are not used anywhere else.
More on sharing can be found here: Sharing
There’s a #wishlist topic asking for more control over shared users which you can vote for and/or comment on here: Multiple Users' Permissions for Shared Users
For now, the 2FA challenge is limited to SMS text messages, so if 2FA is set up on his account, he will need to have SMS ability. The app will stay logged in after the first successful 2FA challenge, but the challenge will need to be completed again after a log out which would include restarting the phone.
Wyze is researching app-based (non SMS) 2FA which would work better overseas. You can read about and comment/vote on that here: Add authenticator app(s) for 2 Factor Authentication (2FA)
Thank you!
And thank you to your husband for his service and to you and the kids for dealing with hubby and daddy being gone!