Kyls, such a difficult task you have and lucky Veronika to have such a caring mother.
Have you tried the blender batter waffles, muffins and cake from Quirky Jo's website? Brown rice is great in these recipes and you would never know what they are made off. With the fermenting they are quite light. I freeze the leftovers straight away as I find they don't keep we'll, but great used on the day from the freezer.
The waffles dont have added sugar, or dairy, and you can make them with chia gel instead of eggs. I have also made the fermented waffle recipe and changed them into savoury waffles using any veggie and spice I felt like.
I think the cake and muffin recipes (from memory) would also be able to be adjusted. I would use dates or bananas for sweetness.
Also have you tried the gf pizzas from Quirky Jo? Mini ones would be great for a snack. I love her Quinoa and chia flatbreads as well. I sometimes cook like a piklet and use for sweet or savoury snacks.
As you can see I love Jo's recipes
Klys, have you tried any recipes using legumes instead of flour? There are quite a few on this site. Some would be suitable to adjust for Veronika. And they do taste good
I hope these are some ideas that might help.