I am looking to send an API request to start / initiate the "update mesh now" process that is built into the Bed Visualizer
Since this is a plugIn, I am not sure if there might be something already there for this or if I will need to somehow create a plugin that has new APIs and somehow create a way to then integrate with the existing BLTouch and Bed Visualizer plugins. Or would it just be better if I just send all the commands to the Printer like the bed Visualizer does, completely ignoring the more or less already completed plugin that I just want to kick off.
My plugin does not have an API for doing the colleciton process, but you can send the same exact gcode settings you have configured in the plugin's settings and it will do the same thing. Some people even embed the @BEDLEVELVISUALIZER command into their start gcode just prior to the G29 to always keep the visualization updated with every print.
an alternative to sending the commands could also be using action commands, but that requires that to be enabled in your firmware.
excerpt from release notes on this feature with 1.1.0.
add custom action command BEDLEVELVISUALIZER_LEVELBED to allow use with various custom config input options in Marlin (Configurationa_adv.h), ie CUSTOM_MENU_MAIN. Will initiate the command contained within the Update Mesh gcode script when received. Requires HOST_ACTION_COMMANDS to be enabled as well. Example menu item.
Thanks for the suggestion, for a simple one off setup, this would be an option. But having to update the firmware would be too high a bar for a lot of the use cases in my design / delivery expectations.