Yes - could do something with salt - maybe a brackish salt solution - around the base in a saucer - but that might leech into the soil - and not be good - the garlic powder didn't seem to inhibit any growth last year - so far - so good - - no slug eaten seedlings -The far one looks like the winner and has made his way through.
My auld fella use to put down salt (as did most people back in the day)
I recall the joy on his face come morning time when the slugs would be abletaraited, I swear he got a buzz from it.
Obviously you can't use the salt in your soil, (will dehydrate your seedling)
But you could make salt rings at the bottom of your pots to stop them crawling up the sides .
Tub of saxa is about a quid. .. (it's something else you will more than likely have at hand)
Those seedligs look fine and dandy man...