Yes, there are loads of Loganair codeshares available, and the easiest way is to book them is via BA.com. Try NCL-SOU as an example. These do not need to be booked with other BA flights, and yes they earn TPs and Avios since they are BA marketed and BA flight numbers. Usually this is an expensive way to do things, but Loganair seem to have a sharp accelarator on their direct sale fares, so from time to time BA sells the flights cheaper than LM. Loganair is one class only.

Note that LM is probably pulls the trigger on cancellations even more than BA, but if that happens you get a full refund and perhaps rebook options.