Tnx for your help.

Before your reply i have used this command:

alberto@alberto-Studio-XPS-1340:~$ pybombs prefix init ~/prefix-3.9 -R gnuradio-default

alberto@alberto-Studio-XPS-1340:~$ pybombs install gr-osmosdr

[INFO] Prefix Python version is: 3.8.5
[INFO] PyBOMBS Version 2.3.4
[INFO] Phase 1: Creating install tree and installing binary packages:
Install tree:
|
\- gr-osmosdr
   |
   +- gr-fcdproplus
   |
   +- bladeRF
   |
   +- airspyhf
   |
   +- hackrf
   |
   +- gr-iqbal
   |  |
   |  \- libosmo-dsp
   |
   +- airspy
   |
   +- soapysdr
   |
   +- rtl-sdr
   |
   \- osmo-sdr
[INFO] Phase 1 complete: All binary dependencies installed.
[INFO] Phase 2: Recursively installing source packages to prefix:
[INFO] Installing package: osmo-sdr
fatal: impossibile accedere a 'https://git.osmocom.org/osmo-sdr/': Failed to connect to git.osmocom.org port 443: Connessione scaduta
error: Impossibile recuperare osmo-sdr
[ERROR] Unexpected error while fetching git+https://git.osmocom.org/osmo-sdr.
[ERROR] Command '['git', 'remote', 'update', 'osmo-sdr']' returned non-zero exit status 1.
[ERROR] Problem occurred while building package osmo-sdr:
Unable to fetch recipe osmo-sdr
[ERROR] Error installing package osmo-sdr. Aborting.

So...another problem ....:

[INFO] Installing package: osmo-sdr
fatal: impossibile accedere a 'https://git.osmocom.org/osmo-sdr/': Failed to connect to git.osmocom.org port 443: Connessione scaduta
error: Impossibile recuperare osmo-sdr
[ERROR] Unexpected error while fetching git+https://git.osmocom.org/osmo-sdr.
[ERROR] Command '['git', 'remote', 'update', 'osmo-sdr']' returned non-zero exit status 1.
[ERROR] Problem occurred while building package osmo-sdr:
Unable to fetch recipe osmo-sdr
[ERROR] Error installing package osmo-sdr. Aborting.