Bringing a wild Ghost-type to 1 HP in Sword and Shield

It's not ideal, due to needing two Pokemon to pull off, but: an Inteleon or Hatterene + a False Swipe user can allow you to consistently hunt ghost-types.

Inteleon (as well as a handful of other water types, most of them more difficult to obtain than the lizard) can learn Soak, a move that changes the target's type to pure water. Hatterene learns Magic Powder, the psychic equivalent. Using this strategy, you can lead with your 'type-altering' move user, use Soak/Magic Powder, and then once the Pokemon you are hunting is no longer a ghost-type, switch to your False Swipe user and attack with the now-effective move.

It takes three turns, rather than the two needed when Foresight was still usable, but if you can't find someone to trade you the Pokemon you need it's likely to end up being faster than having to hunt for a Pokemon with a spawn rate like HA Pangoro's.

(As a note, I don't actually recommend Hatterene for this; Magic Powder won't work on Sableye at all due to its part-dark typing. And even for ghosts she can actually manage to hit with Magic Powder, sending out a lead with the weakness to the type you're trying to hunt isn't a great plan. In the interest of completeness, though, I'm including both.)

You can accomplish this in Sword/Shield by using Pangoro. Pangoro can get the move False Swipe and has Scrappy as its hidden ability.

The description for Scrappy states:

Scrappy causes Ghost-type Pokémon to be hit by damage-dealing Normal- and Fighting-type moves inflicted by the user.

Hidden abilities can only be obtain via raids (or trading/breeding), and Pangoro can be found in Dens 10, 63, 69, 88