I’ll be posting a DIY Huel derivative here shortly (feel free to beat me too it) - https://diy.soylent.com/.
Here’s an example of another recipe (vegan, oat-based) - https://diy.soylent.com/recipes/oats-almonds-rice-1700-male-mix-low-carb
Edit: Another good example AND it’s a bar (though I wonder about the effect of baking on the nutrition) - https://diy.soylent.com/recipes/the-nutty-professor-oatmeal-bars-mostly-supermarket