Just take note that "combo" descriptor is pointless on a WIF private key without the compressed flag byte since the other two SegWit output scripts wont be derived from it.
Otherwise, it'll be non-standard.
You don't have to re-import it as 'pkh' though since it basically did that already, it just skipped the 'wpkh' and 'sh(wpkh)' scripts of the combo descriptor.
I have both a compressed and an uncompressed WIF private key. On the latest version of Bitcoin Core, no matter what commands I tried

, I was only able to add Legacy (Compressed), P2SH-P2WPKH, SegWit, and Taproot... But I couldn't manage to add a Legacy uncompressed address!
I took extreme measures and decided to install version 20.1, where I was able to add a Legacy uncompressed address, but I ran into a synchronization issue.
With 'combo,' it worked right away.