Glad you got it working.
I have been using a Baldr 288Wh Power Station when in the field for three years now. Works fine for me. Never failed.
I also have a bunch of smaller Talencell 5v+12v batteries which I use to power different bits and pieces (like dew heaters, DSLR, etc).
When at home I use generic 110V/12V power bricks.

"When at home I use generic 110V/12V power bricks."

Hmmm, isn't my Bluetti E3BA a "generic 120V/12V power brick?

This put something else on my mind. As you can see in this picture of the Bluetti ,it has both AC and DC outputs and also that something is plugged into one of the AC outputs. That something the AC adaptor for my Raspberry Pi, II came with the Pi and I always thought it was necessary to use it. In fact, I chose the Bluetti BECAUSE it had both AC and DC outputs, and I never thought about it. The AC Adaptor cable plugs into the USB-C port on the Pi. However, as you also can see in the picture, there is a "USB-C 100W" output port on the Bluetti. I wonder, if I just got a USB-C cable of the correct gender, could I plug the Pi directly into that port on the Bluetti without messing with the AC adaptor, and might THAT improve performance of the Bluetti to the extent that the camera would work, since it's no longer needlessly pumping both AC and DC (when the AC would only be converted back to DC by the adaptor)?

Have you tried plugging your pi into one of the USB-A ports?

Your other devices (camera, mount) only on the DC5521 Port and Cigarette Lighter Port?

Just got done with another successful experiment. Bought an "extra-tough", Kevlar coated USB-C to USB-C cable from Ace Hardware and plugged it into the USB-C ports of the Bluetti and the Pi and it works, and it left me capturing objects on the ground.

Such an incredible brain-fart I was operating under for a year and a half. I bought the Bluetti BECAUSE I could plug my Pi AC adapter into its AC socket. So I never even NOTiCED its USB-C socket and never thought of powering the Pi this way. It even worked for awhile that way. And then it didn't.

I only use the cigarette lighter port if I'm using the dew shield which is only rarely necessary in this part of the world. The mount and the camera are powered from the 12V DC sockets on the Bluetti.

We'll give this a whirl tonight.

And Max, your Baldr and my Bluetti are essentially the same thing with different packaging.

"And Max, your Baldr and my Bluetti are essentially the same thing with different packaging."

Yes, this is very likely.
But I never even tried to power my things via Baldr's AC socket.
Always used its USB and 12V outputs.

Based on the (relative) successes I've been having the last two days, and also some bad reviews I've seen, I have cancelled my backorder of the Stellarmate Pro. I say relaytive successes because I am still troubled with being way out of focus and have had poor seeing conditions trying to resolve it, but I have seen enough to know that this is fixable when the weather gets better. Thanks to this community for all your help.

Finally, some good news!

Visiting a fellow astronomer friend who was QUICKLY able to resolve my focusing issues and got the rig working. I'd put it aside for a month in total frustration as I knew we'd be entertaining guests, but now it's back to where it was in November - getting actual images! I'd still like to know how he managed this so quickly.

Happy to see the new AstroArch release, though I think I may wait until I get home to try installing it.