I have a problem with store development. I can't check the store development on Google speed test. Because the password is disabled to turn off.
I have tried with "share preview" but it does still not work.
There is not much you can do if your store is password protected.
Just go live for few minutes while you run your tests.
Too bad, the client wanted to check it out before go-live. I think Shopify should find a way to fix this problem.
You can run Lighthouse reports in Chrome's dev tools on a development store/preview theme.
It's difficult if the client didn't want to remove the password for a while, maybe you can ask Shopify support whether they have another solution about your client's request.