If this is enforced via Play Protect, then the whole mechanism can likely be disabled with:
adb shell settings put global package_verifier_user_consent -1
This does not require root access and prevents Android from invoking Play Protect in the first place. (This is what AOSP's own test suite does, along with other test suites in eg. Unreal Engine, etc.)
I personally won't be doing this verification for my open-source apps. I have no interest in any kind of business relationship with anyone just to publish an .apk. If that limits those who can install it to people who disable Play Protect globally, then oh well.
I really hope this ends up being possible! Play Protect seems to jump up every so often and try to scare me into turning it on. Very annoying. I've wanted to disable Play Protect permanently, but never did the query to learn how, so thank you.
There could of course be side effects in the future when this restriction is rolled out, as in your device's Play Integrity status could be affected and your banking app/phone wallet might not let you perform app-based payments from that device.
I personally won't be doing this verification for my open-source apps. I have no interest in any kind of business relationship with anyone just to publish an .apk. If that limits those who can install it to people who disable Play Protect globally, then oh well.