Ten64's have been shipping for a while now, though you are best to ask in our support forum: https://forum.traverse.com.au/ . We haven't posted much on Crowd Supply as it's a very manual process to get stuff up on there.
I'm not too familiar with TrustZone, but I'm not aware of any limitations in the secure world. I haven't tried OP-TEE or any similar secure world firmware' simply as no one has asked for it.
You can see all our firmware components here: https://gitlab.com/traversetech/ls1088firmware