Lenovo’s Motorola Mobility LLC makes the Signature 27. Motorola Solutions, Inc. and subsidiaries have been separate since 2011.

Pixel 8 devices are the only recommended devices that have “minimum 7 years support and hardware memory tagging support”. I’d personally go with an 8 Pro. The GrapheneOS Usage guide can answer most remaining questions.

If you’re going to wipe your phone anyway, may as well start with GrapheneOS and test your banking apps before setting up everything else to see if it will work for you. You can always revert to stock and flash LineageOS instead if they don’t.