Suppose I have an ADS-B IN on my aircraft and I am interested in receiving also data sent from ADS-B OUT of my own aircraft. Is it technically possible or are there any issues due to the relative position between transmitter and receiver or anything else?
On small aircraft many operators use portable ADS-B IN receivers which typically do not have the ability to sense suppression signals from their own transponder/UAT transmissions and so they will pick up their own signal.
Most installed systems have that suppression functionality so this won't happen.
The suppression is simply a wire between the two units that if the transmitter is transmitting, it goes high, which tells the receiver to ignore whatever it is receiving at the moment.
So if you want to "receive" yourself, simply snip the suppression wire if you have one...