retro@retro:~/RetroPie-Setup$ sudo ./retropie_packages.sh sdl2 install_bin

= = = = = = = = = = = = = = = = = = = = =
Installing (binary) 'sdl2' : SDL (Simple DirectMedia Layer) v2.x
= = = = = = = = = = = = = = = = = = = = =

Downloading https://files.retropie.org.uk/binaries/focal/x86/libsdl2-dev_2.0.10+                                                                                                                        5_armhf.deb.asc to /tmp/tmp.GdEimKTeSB/libsdl2-dev_2.0.10+5_armhf.deb.asc ...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   162  100   162    0     0    244      0 --:--:-- --:--:-- --:--:--   243
Downloading https://files.retropie.org.uk/binaries/focal/x86/libsdl2-dev_2.0.10+                                                                                                                        5_armhf.deb to /tmp/tmp.GdEimKTeSB/libsdl2-dev_2.0.10+5_armhf.deb ...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   162  100   162    0     0    244      0 --:--:-- --:--:-- --:--:--   244
/tmp/tmp.GdEimKTeSB/libsdl2-dev_2.0.10+5_armhf.deb failed signature check:

gpg: no valid OpenPGP data found.
gpg: the signature could not be verified.
Please remember that the signature file (.sig or .asc)
should be the first file given on the command line.
Unable to install binary for sdl2
Errors:
/tmp/tmp.GdEimKTeSB/libsdl2-dev_2.0.10+5_armhf.deb failed signature check:

gpg: no valid OpenPGP data found.
gpg: the signature could not be verified.
Please remember that the signature file (.sig or .asc)
should be the first file given on the command line.
Unable to install binary for sdl2
retro@retro:~/RetroPie-Setup$