Hi Daryl,
good news at first: Your first link was successful! With the custom component it is possible to control those Robotdyn Dimmer boards via MQTT.
The supposedly easy way (making everything with preformed ESPHome components; your second hint) causes a strange behaviour of the board: The motor only starts after unplug and replug the Pump. It runs only at 100% though the logfile shows the correct input percentages of “brightness” like 0-100% (MQTT payload 0-1). Probably the Dimmer module is really buggy.
If so, it would be great if it would be fixed in the future because the options (half cycle and triac management) could be extremely helpful.
Maybe there are similar options in the manufactures library, but this is a task for tomorrow. It’ way after midnight here…