Yes, the T2 always "remembers" its unique ID (ECID) even if you turn Full Security off and on again. It is never discarded.
However, this is really not the question you would like to be asking:
The ECID is burned into the T2 chip and cannot change. The actual signature file created when the operating system is installed is stored on your disk drive as an ...
No, the T2 cannot in any way be used as a TPM for BitLocker. TPM for BitLocker is not a generic term for any type of trusted platform module, but rather it needs to be specifically the Intel TPM specification (latest version is 2.0). The T2 chip does not work in a way compatible with the TPM specification.
Use “Migration Assistant” instead of attempting a direct restore. This mitigates hardware change issues, T2 issues, minor OS difference issues, some software licensing issues, and a few other potential issues.