It looks like moss to me. You can buy moss killer in any garden centre. My DH used to use a pressure washer when we were in our last house. The drive was on a slope, so it all washed away from the house.
Think you’re right about liverwort. Worst place is by front door where the sun very rarely reaches. Thanks for that, nothing to worry too much about. Now to get rid of it!
Table salt - I have got all the weeds and similar out of my big gravel driveway and paved patio for about £3 in total. Boiling water also works. No need for the dreaded round-up!.
I take mine out by hand, it´s backbreaking work but I see lots of life there, worms, beetles, the lot. Any of the suggested remedies, salt, jeyes, round-up, is sure to kill them. All creatures great and small and all that. Am thankful to have them in my small inner city patio.
These days one can buy a weed burner, either electric or gas canister powered, which are safer that the old flame thrower which Bob Flowerdew used to recommend on GQT until he burnt his hedge down! There is a wide range of prices, a cheap version being available at Lidl from time to time. Googling brings them all up.
How do you apply the table salt? My drive on return from holidays is looking very tatty. And since we cut back the yew hedge, sunlight is reaching it and the grass and weeds are growing up fast.