Let me know ....

First of all, it’s GOING TO, not “gonna”.

GOING TO BE GETTING — is said with a certain authority based on a foreknowledge of something you know is going to happen:
— Thank you for your application. You’re going to be getting a call from the company in a few days to let you know if you got the job.

GOING TO GET — is just a fact with no such authority or foreknowledge. As such, it can also serve as a warning of something that may possibly happen:
— If you keep playing video games at work, you’re going to get a letter from the company one day, telling you not to come back. [Here, the speaker obviously has no foreknowledge of this happening and hopes it won’t, but is using it as a warning of what could hypothetically happen. In other words, it doesn’t have the certainty of the above version with the progressive.]

You're such a smart guy) thank u!)

👍🏼🤩