Hi,
Try this: https://realmacmods.com/product/macbook-pro-nocrash-utility/
I have “rescued” 3 systems with this utility. Apple wont even acknowledge the problem (which is why I’m not bying from them ever again.
The CPU has several power states and voltages. Some CPU’s become unstable at extremely low voltages on one of it's cores. The CPU will sometimes briefly dip into that power state, and if it happens to be on the core wherein it is unstable you will see the “silent” crash.
The reason that the hdmi trick works for some cases is f. ex due to dual gpu systems, where an hdmi display will force the system to use the dedicated GPU, which again results in the above mentioned state not occurring. This can also be achieved in dual gpu systems by removing the kext of the internal intel GPU in \System\Library. The result is the same.
It will be the best 10$ you ever invest.