Startup disk not found

Hi,

As for startup issue: If your MacBook Pro has Intel processor, resetting NVRAM could solve your issue.

Reset NVRAM on your Mac - Apple Support

As for WiFi issue: If your MacBook Pro has Intel processor, you could connect to your WiFi access point, start up your MacBook Pro with "Option + Command + R" or "Option + Shift + Command + R"

If your MacBook Pro has Apple Silicon:

1. On your Mac, choose Apple menu  > Shut Down.
2. Wait for your Mac to shut down completely. A Mac is completely shut down when the screen is black and any lights (including in the Touch Bar) are off.
3. Press and hold the power button on your Mac until “Loading startup options” appears.
4. Click Options, then click Continue. 
5. If asked, select a volume to recover, then click Next.
6. Select an administrator account, then click Next.
7. Enter the password for the administrator account, then click Continue.
8. When the Recovery app appears in the menu bar, you can choose any of the available options in the window or the menu bar.

Use macOS Recovery on an Intel-based Mac - Apple Support

Use macOS Recovery on a Mac with Apple silicon - Apple Support

Connect the laptop directly to the router using an Ethernet cable. You may need an appropriate Thunderbolt to Gigabit Ethernet Adapter if the laptop does not have its own Ethernet port.

If you have access to another Qualifying Mac, then you can create a bootable macOS USB installer using the instructions in this Apple article:

How to create a bootable installer for macOS - Apple Support

You will need to know the exact model of the Mac so that you/we can determine which versions of macOS are compatible with the laptop in order to identify a Qualifying Mac. A Qualifying Mac is one which can run an OS the other laptop can also run. You can get the exact model by entering the system serial number here:

Check Your Service and Support Coverage - Apple Support

This article can identify Qualifying Macs since it shows which versions of macOS are compatible with various Apple hardware:

https://eshop.macsales.com/guides/Mac_OS_X_Compatibility

Or you will need to figure out why you cannot connect to the WiFi. You did not provide any details on why you cannot connect to WiFi or how it fails with the WiFi. I can imagine multiple scenarios here.