Baseline observe. You're beside him for everything. Watch where he pauses and where he flows — that's your data. No pressure on him or you to go solo yet.
He drives 5 minutes. Pick one step in Together 1 and hand it to him — "you read that bit to me." Note whether he needs prompting to start.
If he shuts down or gets sharp — drop a rung without comment. Don't name it. Just step back in. Collapse = information, not failure.
If you need to reset Talan's progress on this device (e.g. starting fresh after testing):