Cant help you, but, I can tell you, we are both in the same boat today. I have one, that looks similar to another I have in another area. But that one pops apart very easily. I havent figured out the one with the light bulb that needs changing yet. Tomorrow is another day.

Grasp the glass dome in both hands and turn counterclockwise. It's a friction fit, so it will probably take firm pressure to get it to turn. Once you get it fully turned, probably about an eighth of a full rotation, it will bump into a stop and it should drop straight down.

Use one of those grippy silicone jar openers

Or rubber garden gloves work great.

pull the entire thing out - if you can't get a grasp of the rim, use a butter knife to gently pull the fixture out.

The fixture doesn't come out. It seems to have a lip that expands inside the rim. The only way I could see it working is if the actual rim cam out, but I'm afraid of damaging it.

Yes, the rim comes out. I have the same fixtures (edited to add: actually, not exactly the same, but very similar). Slide the butter knife under the rim, move it around the entire edge gently tilting the knife every 1/2 inch or so to separate it from the ceiling, and then pull. There will likely be metal pieces on a spring - once you can pull it out about 3/4-1/2", you'll be able to move the metal spring-ed "holder pieces" (technical term) with your fingers to pull that entire piece - rim and central cover - out to access the bulb.

Here's my (very similar) light fixture:

This is what it looked like after I pulled off the cover, with rim and took out the light bulb.

And this is (upside down) the rim and cover, which come out in one piece. See the metal pieces? They're on a spring and they hold the piece up.

Ps: I didn’t actually have to use a butter knife for mine, my finger nails worked fine to ease the rim out.