I know of one "no kill" breeding flock which just about scrapes by most years. It's the Doulton Flock of rare breed Border Leicesters, Ellie Stokeld claims that she sells all lambs for breeding or fleece homes, and she and her helpers put an enormous amount of effort into marketing their own wool for crafters. There is a waiting list for the truly awesome fleeces, they also produce fibre ready for spinning (which is very popular with spinners, it's as gorgeous as the fleeces and easier/quicker to get spinning!), and yarns for knitters and other crafters.
in order to sell all your spare lambs for breeding, you need (a) a demand and (b) a name. Ellie shows her sheep, wins prizes, therefore has a "name" and is able, she claims, to sell all her non-retained lambs for breeders. I think a lot of Ellie, her sheep and her products, but in truth I remain sceptical about all male lambs truly finding breeding homes. However good you and your sheep are, not all ewe lambs are suitable for breeding and only a relatively small proportion of tup lambs should be bred from. If you breed from everything, the stock will deteriorate - to me, the basis of a healthy flock is in who you don't breed from. And if you sell substandard animals for breeding, all your hard work establishing a "name" will soon evaporate. So I have never understood how this aspect really works as Ellie says it does, and suspect that, at best, most of her male lambs go to small flocks, to be used once or twice and then eaten before they are coming onto their daughters. But I do believe that she herself does not slaughter anything, and personally I think you can't really do more than that if you want any numbers and want to breed.
To produce and sell the woolly products for more than the Wool Board's price is also a huge amount of work (and expense up front for the processed products.) As well as showing her live animals in order to maintain her name as a breeder, Ellie also does all the woolly shows, operates a very active Ravelry group and has a presence on Facebook.
In good years, Ellie gets by. But when the jeep needs replaced, or the tractor needs expensive parts, or the wool shows are all cancelled because of a pandemic, etc, etc, then she has to get the begging bowl out and try to crowdfund the necessary expenses. Because of all the hard work she does marketing to crafters, she does usually manage to raise monies this way, but to me, operating a large flock of sheep with the risk that you will not be able to afford necessary expenditures to keep the sheep fed and happy is a potential welfare issue, and personally I could not operate that way.
Another option is the charity route. One of the best examples I know is the Woolly Patchwork Sheep Sanctuary. Charlotte rescues sheep and gives them forever homes, does not breed, and again, works very hard marketing to crafters through her website, Ravelry and Facebook. The fleeces from some of the sheep at least are pre-booked, and all the ones which are suitable for spinning seem to sell for a reasonable price each year. I think you can "adopt a sheep" for a year or its life, and get updates about it, that sort of thing.
If you limited your incoming sheep to those with fleeces that would interest crafters, then that would potentially be a way to cover the costs of keeping sheep that aren't for meat.