Text on a path using Affinity Publisher is the only way I can see how to do it using Affinity menus. But then that's been in Publisher since release.
The only other way I think in Designer is to create the text, convert to curves, ungroup group, add as curve, press A then individually pull the nodes to a projected path holding shift.
It's not fun. Affinity must be holding out until version 2.0. There is no logical reason we should be waiting five years for this feature.