When zoomed out, I see only bar numbers, e.g. |13 |14 |15 |16 ...
When I zoom in more, I see beat numbers in between the bar numbers, e.g. |13 |2 |3 |4 |14 ...
Zooming in even more, I finally see tick numbers in between the beat numbers.
So if you’re asking whether Ardour can show beat numbers (1.2 being the second beat of the first bar, for example), the answer is that it already does. However, I don’t know if you can change how the beat numbers are formatted.