I think they're referring to the thermal throttling, and not the MBP forcing the discrete card when an external monitor is connected. As far as I know, there is no way around using the discrete card for external monitors (on my 2015MBP at least, I'm pretty sure the HDMI port is wired direct to the M370X).
I've solved the thermal issues by using an eGPU (like GP suggests)
When it works, its great which is about 50% of the time. When it doesn't and for no apparent reason, it will often reboot a couple of times (just when plugging in the displays).
Sometimes the banding issue that the M1 Mac owners have described appears on one or both of the displays.
A pretty frustrating experience.
Already running discrete graphics all the time so no auto-switching.
If it’s useful: It’s fine here including reasonable loads on the video card, like a lot of GPU-accelerated terminals and pretty heavy use of a tiling window manager and Exposé window swishing. Or, say, Sketchup in a browser? Plus a pretty serious IntelliJ setup with the JVM’s stops pulled out, running ReasonML and C++ source compilation, and use of Docker.
It is sensitive to setup, and I can get it to spin its fans up. Docker is especially prone to wasted cycles. And I did seem to have to do some SMC resetting at one point because the fans were a little eager to get going. I also think it makes a bit of difference if I charge through the right-side ports rather than the left.
But the main point I’m attempting to make: I do think your case is solvable.
That said, I have felt that Apple are losing their way in some respects. The fact that there are fan issues with some machines and that it’s not clear how to solve them is a problem with these machines.