Hi @pieterg did you take a look at Hover on Axis Tick Label? Since hovering on ticklabels is not supported, you can fake it either using the hover on points, with hovermode='x' (for example
import plotly.express as px
fig = px.scatter(x=[1, 2], y=[1, 2], hover_data=[['loooong1', 'looooong2']])
fig.update_layout(hovermode='x')
fig.show()
), or you can add a second trace with invisible points at the location of tick labels.