I haven't watched the video

I would generally rather have text form content

but if Rossman is announcing the same thing that I just read about elsewhere, it's not a removal of sideloading. It requires that a developer register and provide Google with personal information for Google to let them create packages. Assuming that Google is willing to let the F-Droid developers register an account (which I assume they have) and sign the F-Droid package, it should not restrict installation of the F-Droid package.

However, you wouldn't be able to use F-Droid to install any packages that didn't conform to Google's new requirements.

I doubt that the restriction is at the store app level, but at the package installation level. That is, I would expect that the F-Droid or Google's store app or whatever says "install this package" and the OS refuses.

https://developer.android.com/developer-verification

Starting in September 2026, Android will require all apps to be registered by verified developers in order to be installed on certified Android devices.

Step 1

Verify your identity

You will need to provide and verify your personal details, like your legal name, address, email address, and phone number.

If you're registering as an organization, you'll also need to provide a D-U-N-S number and verify your organization's website.

You may also need to upload official government ID.

Step 2

Register your apps

You'll need to prove you own your apps by providing your app package name and app signing keys.

My suspicion is that the main purpose of Googles decision is to stop F-Droid and Aurora Store from working.

You can use F-Droid and other install sources on alternative ROMs.