There are a number of Moodle plugins that provide a whiteboard-like feature, but I cannot see any of these on the OpenLMS plugin matrix
In truth, most organisations use the whiteboard that is built into their preferred live conferencing technology - Zoom, Teams, Collaborate, WebEx etc, BBB. Often times, whiteboard activities are conducted in real-time, so these technologies are well suited.
For asynchronous collaboration, you can simply create an open-access room that has no start and end date.
If you are happy to take this work outside of Moodle, there are a range of online white-board style collaboration tools. 7 best online whiteboards for team collaboration in 2021 | Zapier14