Great website and kudos for making it. Noting you have limited spare time feel free to ignore but: I would love to be able to select a collection of exercises and see a visual of which muscle groups I do and don't have covered in the chosen exercises. Perhaps with some suggestions on exercises to cover those that are missing.
Yeah, very reasonable question. I suppose a somewhat simple version could be to add exercises to a 'cart' and then change the colour muscle groups on the home page based on cart contents. Would then be pretty easy to click back and forth and colour in the desired groups. If I could then look at my cart when I'm happy I have good coverage that would probably be enough for my needs of 'does my workout plan have any blind spots'.