Honestly, if you're going to do both, do bluesky and mastodon. Bluesky isn't properly decentralised the way mastodon is, but a lot of influential people are there. Also it's way better than twitter was.

You need to use a different device and IP address. IP addresses are a dead giveaway for someone trying to create a second account, and even with a different address, browsers are easy to reliably fingerprint.

The reason for using an entirely different device* is to prevent advertising crap baked into your software from sending Twitter or other platforms any unique advertising ID associated with one of your old, banned IP addresses.

*With careful setup, a virtual machine with a dedicated VLAN and internet connection would work.