I like canola oil as a fat source (it’s what I use.)
You can also consider peanut butter, if using a blender - I hear the flavor is great. Just cut your carbs and protein based on how much you’re adding via peanut butter
I would skip the amino acid supplements… they may be helpful if you are on a very restricted amount of protein, but you’re eating ample protein. BCAA’s, especially, are popular in muscle mags and in broscience, but the truth is that there’s plenty of BCAA’s in the protein powder you’re taking. Given the high protein intake you’re talking about, the amino acid supplements are completely superfluous. It’s like adding a pinch of salt to your cup of salt.
For fiber, psyllium husk is cheap, well-known, and works great. Mix it in dry, and it mixes easily. Just don’t pour water directly on a spoonful of psyllium husk which is against the side of your container, or you’ll make a sticky glob which will take a long time for water to saturate. If mixed while dry, it works great.
I think the maltodextrin is fine, especially when mixed with all the protein, fat, and fiber. Non-concern, to me.
+1 on this. Fearing that there’s any food which will “give you” celiac is completely unfounded. There’s no reason to believe that. Use wheat or wheat flour if you like it, don’t use it if you’re celiac.
Likewise, don’t use the peanut butter if you’re allergic to it… and if you’re not allergic, you don’t need to avoid peanut butter for fear of becoming allergic to it.