My Precision T1700 has Intel Xeon E3-1271 v3 CPU (Haswell).
Any word as to whether 'Intel PTT' or TPM 2.0 will be supported?

Currently shows as TPM 1.2 in Windows 10.
From reading other posts it would appear that Haswell or newer, should be capable of supporting Intel PTT.

Trying to establish if I will be able to install Windows 11 (without hacks).

There are currently no updates for TPM 2.0 listed in the support section for this machine.