The Jye Tech DSO-150 is a compact scope available as a kit that can be upgraded with open source firmware.
The Open-DSO-150 firmware offers various features including one analog or three digital channels, configurable triggers, voltmeter mode, serial data dump, and signal statistics display.
For more details on features, visit the GitHub page and firmware can be built in Atollic trueSTUDIO STM32 version.
If interested in the factory version, a review is available, and users can share their scope hacks with the community.