Hi
@Abid, welcome to Computer Forums!
Opening the laptop in theory shouldn't void the warranty if there are no stickers, but certainly it's possible to find out what disk is currently installed.
The easiest way would be Device Manager and look under Disk Drives, or just go into This PC in Windows Explorer and right click the C drive, select Properties and then click Hardware.
This will give you the make/model of the current disk drive. Usually the drive technology is indicated, e.g NVME, SSD, but if it isn't, just search the model of the disk drive to find out what it is.