Just to throw my 2p in here and give some feedback on the 8gb models - I've got the 8/8/512 MacBook Air with 8gb ram. I'm a fairly demanding user, my thinking was I'd see how I get on with the 8gb, expecting to return it and upgrade to a 16gb model during the extended holiday returns period. To be honest, having used it flat out for everything for a week now I'm really not sure I'm going to bother. I've used Lightroom Classic with 42mp files, multiple 4k streams editing in Final Cut Pro, multitrack audio in Logic Pro and it honestly flies. I'm running the latest beta version of Microsoft Office which are built for Apple Silicon, and they use quite a chunk of ram (especially Outlook) but I still get no slow down when using the machine. I'm genuinely surprised and that doesn't happen very often.
The advice of going with 16gb ram for the long haul is sound advice, and I may still do just that, but I think Big Sur has been so well optimised for the M1 platform that it's really not anywhere near as much of a requirement as it would be on Windows (or an Intel Mac for that matter).