You can toast the bread directly from the freezer. It’s helpful to put slices of bread in zip lock bags so that you don’t have to try and break off slices when it’s frozen. You can then either microwave for 10 seconds at a time (as to not dry out) until thawed or you can let thaw in the fridge (usually 2-3 until hours). Same with bagels, buns etc.
We use a combination of almond flour , flax meal and oat fiber to keep them very low in carbs and still taste good.
Net carbs are the total carbohydrates minus fiber and sugar alcohols (in our case we only use high-quality erythritol).
The FDA requires US labeling to include fiber and sugar alcohols in the total carbs unless most other countries in the world who subtract already to give the net carb count.