Can't Reset PRAM with Apple Wireless Keyboard.

A bluetooth keyboard may not become active soon enough for special pre-boot key combinations.

Unless you are booting into Recovery Mode you will need to use the second command which includes "sudo" to run the command with admin privileges. This command works on all Intel Macs and all recent versions of macOS including Big Sur.

You can confirm the settings are wiped by using the following command immediately after the one @Sharhari suggested:

nvram  -p

which should not display any settings after running the "sudo nvram -c" command. Make sure to reboot the computer after issuing the "sudo nvram -c" command so it takes affect.

If your Mac chimes, then you need to hold the PRAM Reset keys immediately after the startup chime. If your Mac does not have a startup chime, then you need to hold the reset almost immediately after the computer powers on. Timing is much harder to get without the startup chime. Hold it too soon and the computer may not boot or it may ignore the keys entirely. Hold it too late and you miss the window of opportunity.

You can reset the NVRAM/PRAM via Terminal (although you will still need to restart) just bring up a terminal window and type:

nvram -c

or

sudo nvram -c

Hope it helps

So you are saying type one of those into Terminal, and then restart? Cause I have the same problem, even when using a USB keyboard, which should be able to engage quickly enough, but apparently doesn't, cause when I press the keys, it still opens the usual way... At least now, the chime sound is back, so we can tell if we're getting that second chime....

Yes, depending on user rights that should work. Newer Macs may have different procedure or command.

In other cases contacting Apple support directly is the best thing to get the issues / problems fixed.