For a brand-new watch, you need to follow the instructions here produced by @fanoush. Also following these instructions downgrade to SoftDevice S140-6.0.0. After that you can flash the zip file from the firmware directory.
IMPORTANT - you need to downgrade the SoftDevice before loading my Espruino zip file. The sequence is is this: install 1) Espruino using DaFlasher 2) DFU bootloader using WEBIDE 3) Espruino zip file from fanoush repository 4) downgrade SoftDevice to 6.0.0 5) Espruino zip in this repository. Miss any of these steps results in a temporary (wait for battery flat) or permanent brick.
This build has a modified lcd_spi_unbuf module. The build makes the full 8 megabytes available to Espruino applications.
For a brand-new P8, you need to follow the instructions here produced by @fanoush to get the right bootloader required by Espruino - SDK12 with Softdevice S132 3.0. After that you can flash the zip file from the firmware directory.
This build has a modified lcd_spi_unbuf module that works with SPI FLASH. The build makes the full 4 megabytes available to Espruino applications.
Once Espruino is installed use the App Loader to load Bootloader, Main, Launcher and Settings followed by the apps and widgets you want.
These provide a simple Bangle emulation environment which will let you load Bangle Apps from its App Loader.
Note: If you want to connect GadgetBridge from an Android phone load the Android Integration and Messages apps from the official BangleApps loader.
@ATC1441, reverse engineered the DaFit app and wrote DaFlasher which allows you to replace the firmware these watches come with.
@Fanoush, for the Espruino builds/bootloaders and his help with getting the LCD driver to work.
@gfwilliams, for Espruino and for the Bangle App Loader used here. If you want a hassle free watch you can program off the shelf get a Bangle.js or Bangle.js2.