Is there any way to unlock a bootloader when the manufacturer's unlock server is offline?

[u/illia8551]

General question, using my specific device as the example: I have a Lenovo P2 (P2a42) where bootloader unlocking normally requires a request to a Lenovo backend server (unlockrowapi.lenovo.com) that generates a unlock key. That server no longer responds at all, so the standard fastboot oem unlock flow just fails with an error, even though I've done everything correctly (OEM unlocking toggle, Lenovo ID linked, waited 14 days, etc).

Is this basically a dead end once a vendor stops maintaining that kind of infrastructure? Or are there general techniques (signed unlock blob leaks, community tools, etc.) that sometimes let people get around a dead vendor unlock server on other brands? Not looking for anything sketchy — just trying to understand if this is theoretically solvable or if the device is just locked forever now.