Visible officially enabled unlimited mobile hotspot (throttled to 5Mbps).
However, the official FAQ states this is a feature that's enabled during the "early access" period and therefore it may or may not be included (or included for free) when the service officially launches to the general public in the future. The FAQ also states only one device at a time may connect.
Updates to this story:
[…] Visible has deemed plan polices as 'limited time.' For example, their mobile hotspot option, first offered back in June 2018 (a month after the Visible service was officially first offered), was advertised as limited […]