My 16" MBP is about 3 or 4 weeks old at this point - my first watchdog lockup happened right after upgrading to 10.15.2. I had a 15.4" MBP running Mojave and used the wireless migration to move my data.
I've had 1 - 12 lockups a day, doesn't seem to matter what is plugged in. Last week it locked with just the power cord plugged in. Sometimes the lockups occur when I've walked away, so can't blame anything I'm doing while in front of the computer.
This week I tried to go back to Mojave, only to find that you can't install an earlier version of the OS than what was shipped with the computer. So I re-installed Catalina using the internal partition and then allowed it to restore from my Time Machine backup.
It's been a little over 24 hours, but I've had it running with a Windows 10 VM with applications executing constantly, with the Time Machine external drive plugged in, and an external monitor. So far, so good.
Based on other comments here, I'm wondering if the root problem may be the image that the factory laid down. My re-install seems to have worked. If it appears again, I'll post an update. It's been 3 weeks of misery. Normally I would have waited a couple of days to report it, but realistically, given how hard I'm using it now, it would have locked by now and I know a great number of people are having similar issues.