If there are two HALOW APs, one at point A and one at point B, will the Client AP connect to the AP at point A when it is closer to point A, and to the AP at point B when it is closer to point B, enabling roaming functionality?
Short answer: there is no standard for client roaming behavior
Long answer: A HaLow client is just like any other 802.11 client per se. However, each client device manufacturer has its own algorithm for the criteria on when to roam and where to roam to. And the algorithm can change between firmware versions on the same hardware. Some manufacturers document the algorithm and some don’t.