All this info taken from JSONs found in Chromebook recovery utility extension.
Links leads to ZIP files containing BIN files, which are themselves GPT images, ready to load to USB drive using utilities like dd or Rufus (in dd mode).

Below is two drop-down lists: one is list (json file), other one is selector of image from list. You may put focus on the selector by pressing Tab key and switch elements with Up arrow and Down arrow keys.

Description of lists

cloudready_recovery	Stable ChromeOS Flex builds
cloudready_recovery2	Stable and dev ChromeOS Flex builds
onhub_recovery	ChromeOS builds for discounted Google OnHub wireless routers (Google Wifi, TP-Link TGR1900, ASUS SRT-AC1900)
recovery	Stable ChromeOS builds for various models
recovery2	LTC, LTR and stable ChromeOS builds for various models
workspaceHardware_recovery	Stable ChromeOS builds for Meet Compute System (all-in-one PCs)
workspaceHardware_recovery2	Same

Thanks afraid.org for free domain.