There is control.getConfigValue API that you can use to probe the board the same way the runtime does. You can drop current.uf2 from your board on https://microsoft.github.io/uf2/patcher/ to see actual config of your board. You should be able to use control.getConfigValue(DAL.CFG_BOOATLOADER_BOARD_ID, 0), however some manufacturers just clone an existing config and you end up with multiple boards with the same ID. However you can query other things, for example control.getConfigValue(DAL.CFG_NUM_NEOPIXELS, 0). Feel free to wrap this up in an extension!
If you drop wrong UF2 it will be ignored, due to family-ID feature, see https://github.com/microsoft/uf2#family-id