It is very difficult to make low carb bread as all the usual ingredients are high carb.
I have been experimenting now that my levels have been normal for a while and tried adding into my normal bread recipe psyllium husk powder and milled seed mixture I got from Lidl - though they seem to have stopped having it at my local store - it was 200gm of mixed linseed chia and hemp seed.
The flours I had on hand were normal white bread flour, rye flour and chapatti flour, which is made from millet, I think, so I used two cups, US style measure of bread flour, one of rye one of chapatti, the 200gm of milled seed, a cup of psyllium flour, a little salt and lard, mixed it to a wet dough with boiling water and let it sit overnight, then next morning I kneaded in twice the usual amount of fast acting yeast and put the dough in the tins, covered the surface with oiled clingfilm after wetting it, and left it in a warm place to rise. That made almost twice the amount of bread as the usual recipe, and once it had risen I removed the clingfilm and baked it at about 180 degrees as the seeds burn at the normal setting of 200 degrees. I used the same sized tins as usual and so got smaller slices. It was not like my usual bread of course, but the carbs were less.
The clingfilm did seem to help contain the CO2 better than the first time I tried it but it needs careful handling.
Quorn seems to be OK, but things made with Quorn have had carbs added and so need careful scrutiny of the labels.