The non-cloud methods for recovering the key have been the same since Bitlocker was released 19 years ago.
https://support.microsoft.com/en-us/windows/find-your-bitloc...
https://support.microsoft.com/en-us/windows/find-your-bitloc...
There other 2 options are enterprise or online account (the very thing we're talking about) don't apply in this context.