"The rules around the Alert feat specifically and literally say the character cannot be surprised, in essence the character has nerves of steel and can be ready to act on instinct if necessary. As soon as the sorcerer player declares intent to initiate combat, initiative is rolled. As far as I know, there is no freebie round where PC's or NPC's get to act freely and do whatever they want. If a character is surprised, he simply looses the ability to act on his first turn, it does not mean initiative is not rolled."
I very strongly disagree.
It means that you can use move and reaction on first turn . Nothing more. Not being surprised is just that and nothing more.
"I am never surprised."
Congratulations, you can move and reaction on your first turn. That's it, nothing more.
So, you can't roll initiave against hidden creatures and undetected subtle spells for obvious reasons, it remains hidden.