Officially: Kind of, sort of, maybe.
You can’t natively assign a different top-level domain to a Streamlit Cloud app, but yes, you can do some trickery with a frame or redirects. Results may vary depending on your registrar and the specifics around the security certificate is the stickiest point. I think the frame route is the most reliable.
You will need to know about embedding apps, as you can get into a “too many redirects” situation without including the embedding argument in your url.
Here’s an option with a frame:
I believe I tried multitude of combinations with my own DNS as I mentioned in the linked and didn’t have any luck, but I can’t find my write-up explaining the full experiment at the moment…