I bought a second hand MacBook Pro . Tried going to recovery mode and there’s no startup disks AT ALL!

What is the exact model of the Mac & version of macOS? If it can boot normally, you can get this information by clicking the Apple menu and selecting "About This Mac", otherwise you can get the exact model by entering the system serial number here:

Check Your Service and Support Coverage - Apple Support

If the laptop can boot normally, then look to see the information for the internal boot drive. Check the System Profiler by Option-clicking the Apple menu and selecting the top option. On the left pane of the System Profiler, click "NVMExpress" to see if there is any information listed on the right pane. If so, then please post a screenshot here. Most Apple SSDs will show Apple as the manufacturer.

When booting to the macOS installer, what OS is being proposed to be installed?

If this laptop contains a third party NVMe SSD, then you will need to boot macOS 10.13+ in order for the installer to see the third party NVMe SSD since older versions of macOS lack the driver necessary to communicate with an NVMe SSD.

If you are booted to a macOS 10.13+ installer, then within Disk Utility click "View" and select "Show All Devices" in order for the physical drives to appear on the left pane of Disk Utility. If you don't see a physical internal drive, then there is some sort of hardware issue.

Hi,

Resetting NVRAM could solve your issue.

Reset NVRAM on your Mac - Apple Support

Go back to the reseller and put the question to them. If purchased on eBay request a refund asap.