I think I can take an educated guess - but it would be good for the manufacturer data sheets (on RS etc) to say which supports which.
What is ANZ915? is it the AU915-928 band? Australia & New Zealand perhaps? (guess)
does AS923 support both AS920-923 (“AS1” - Japan, Malaysia, Singapore) and AS923-925 (“AS2” - Brunei, Cambodia, Hong Kong …)
Are these TTIG devices all the same hardware? - or are there different hardware versions for each? somewhere inbetween?
Can I download software / configure a TTIG to a different region?
I’m making a multi-region LoRaWAN tracker (GPS geofences Region) and I wanted to test without shelling out a fortune in different gateways.
You can’t do that anyway as you’re not authorized to radiate on the wrong-region frequencies.
Test gear utilized by manufacturers who actually do this connected the node to the tester (not a gateway) via a shielded cable; no antenna is involved.
Generally speaking the TTIG isn’t what you want for node debugging anywhere as it doesn’t readily expose raw information to help you diagnose what is going wrong when things are not working well enough for the complete pathway through decoding on the TTN servers to work.
Dubious you’ll achieve the shielding effectivity you think (and remember the TTIG is wifi only, so you’ll need an AP in the room, too, plus there are issues with it disconnecting when idle) but if you insist on pursuing it I think you’re really, really going to want a pair of conventional concentrator cards for each band and a host Linux system where you can tweak the software. Two cards and a pi will cost less than two (or more) TTIGs and many headaches.
To be blunt, the TTIG as a product has been a huge disappointment in terms of what it can do and how well it works, compared to what the community needs and the way the TTIG hardware could have accomplished that.