I have retested the same version of Veracrypt on Ubuntu 23.04 and I see after step 6 above when I enter encrypted volume password, new dialog is opened to ask for “admin” password. I type in password, this is the password for user with sudo/root privileges and then volume mounts.
I see in Fedora Siverblue “admin” dialog to enter sudo password does NOT open at all, but instead error is returned, like described in step 6.
Inside container I tried to start program with: sudo veracrypt but I have got the same error like in step 6.