Another point of view, since I am also a Bascom programmer, it was almost quite easy to start with MMBasic for Pico, called PicoMite. However, the disadvantage is that it is an interpreter, so you have to load the whole interpreter into Pico and only then write Basic programs. Of course, there are many examples on the web, but also a good manual for PicoMite. There you'll find HD44780 as well. Still on my todo list is to make some example with Pico and visualisation datas on pc side using pas2js (lack of time or i'm too lazy to do it)