This is really the most secure option and one that meets security needs. I agree it's important.

Most of our customers use MFA, and the -Browser option in Connect-Site is not really an option. Should support other ways to authenticate.

We are soon starting a massive migration (several thousands of site collections) and have everything automated so far, except the login part for ShareGate. If we cannot sign in unattended to SharePoint M365 we won't be able to recover from a script failure. Besides every night / weekend someone has to sign in for the script to run.
An authentication method analog to PnP / Microsoft using a client id and a client certificate / secret would be highly appreciated.
Would be great to hear from you.

Now that Microsoft is actively depricating the old/classic authentication mechanisms on M365 tenants, it’s urgently needed to be able to authenticate based on AppId/secret/Certificate. The reasson is that the only currently available safe way to authenticate is -Browser, but in a non interactive context (deamon, process, job) this is not applicable. This is the reasson SG PS script is used in conjunction with ShareGate most of the times..
Other solutions could be to be able to set up a connection with PnP but re-use that connection with ShareGate Get-Site. But in any case.. this situation was looming since 2018, and it’s getting urgent.

It would be ideal to leverage AppID, Certificate Path, and Certificate Password. Or Better yet support all authentication mechanisms similar to PnP.PowerShell

This would be very useful, as we are doing a lot of scripted migrations but most on most environments only MFA enabled accounts are allowed.