I only plan to use it for messaging in a couple of sports teams and event invitations.
I’m willing to take a lot of measures as long as they don’t get the account blocked - no phone app, dedicated virtual machine+VPN to isolate from other internet activity, purchased fake phone number in signup, adding fake interests and life details. However, I won’t provide any real ID/photos, are these needed for signup?
Getting a burner phone and account and only tun it on when you want to check the messages is a good start. Do not use any of your real information.
When I left FB a decade ago they didn’t force a phone number for the messenger, thy basically just requested all possible permissions.