At the same time, as a comparison, I tried to receive using an RTL2832 SDR receiver (NooElec R820T2) which appeared only a little worse than the RSP1, probably because of the reduced number of bits (8 bits vs 12 bits samples). 

For this test I received the 144.8 MHz with a multi band discone antenna, and the GQRX software on Ubuntu 22.04.

I started testing the SA818v 144MHz FM transceiver module, which appeared very cheap (around 15 Euro) and simple to configure. I haven't tested the TX side yet but, after some struggling, I understood that the RX sensitivity (declared -124 dBm) was insufficient  in my situation. In fact two APRS iGates that I received at around -40dBm with my Sdrplay RSP1, were barely listenable and not decodable using the SA818v receiver.

For this test I sent the audio output from the SA818V or from thr Sdrplay RSP1 to the GQRX SDR receiver (which has built in AFSK 1200 decoder) on Ubuntu 22.04  or to the Direwolf software

Sources

I collected two initial hardware resources using ESP32 and SA818: https://oshwlab.com/APRSTH/esp32sa818#P6  https://github.com/nakhonthai/ESP32IGate/blob/master/doc/ESP32DR_Simple_Schematic.pdf

and two software: https://github.com/erstec/APRS-ESP https://github.com/nakhonthai/ESP32IGate

and I'm now trying to receive some RF APRS messages on 144.8 MHz to test rx capabilities.