- follow the "install the sdk manager" steps https://developer.garmin.com/connect-iq/sdk/
- download SDK "Connect IQ 6.3.0" and set as "Current SDK"
- download Device "Watches/Wearables Fenix 6S Pro / 6S Sapphire / ..."
- adjust ENV.BAT:
  - for generating the developer key, read %SDK_PATH%/CoreTopics.html#developerkeys

to run in simulator:
- run BUILD.BAT
- run STARTSIM.BAT
- run RUNINSIM.BAT

once the simulator is started, it can be kept running. Just push the "back" button (bottom-right)
to exit the app, and re-run BUILD.BAT and RUNINSIM.BAT without closing the simulator

to put on actual device:
- run BUILDRELEASE.BAT
- connect device with cable to pc
- copy "bin/r25.prg" into <device>/GARMIN/APPS
- disconnect the device and let it process
- push the "start activity" button and it should be in the list

to build for other devices (untested):
- find your device in %SDK_PATH%/ReferenceGuides.html#devicereference
- add its id as an <iq:product> entry in manifest.xml
- the device probably also needs to be downloaded in the SDK manager for building to work
- (boing ball may not draw correctly because it's in a resources-round-240x240 folder,
   perhaps this should be changed/copied to a folder that fits your device's specs too,
   again see the reference because it mentions all devices' shapes and sizes)

PUSH2SIM.BAT and SHELL.BAT are leftovers from when I was trying to figure out how to
use the simulator without using the official VSCode extension, before I found out the
docs shipped with the SDK contain instructions

final note: the source is mainly written in https://github.com/yugecin/Jeanine/
which is a 2D editor. The code is still a mess, but has a slightly better visual
structure when viewed using that editor.