I am by far not an expert on mimblewimble but want to dive in deeper soon when the grin mainnet launches.

The way I have understood it, mimblewimble does not have pay2scripthash and thus the standard lightning implementation cannot be realised. I also believe that the way mimblewimble works there are theoretical barriers to implement scripts and anything beyond direct payments. So currently it seems not possible, until someone much smarter than me discovers some needed cryptographic methods.