These can be smoothies, bars, drinks, supplements, etc.
Is there something specific you look for (ex. price, ingredients, specific nutrients etc.)?
Is there a brand you like / avoid (ex. soylent, huel, hol food, etc.)
Edit:
I definitely don't recommend fully replacing your diet with them. I know some people use them instead of other processed food / fast food / skipping meals entirely, and that's the use case I had in mind for myself
I make very easy shakes in my nutribullet which are just water, ice, oats, chia seed, protein powder with probiotics, peanut butter and some berries or a banana. I swap in some other things like hemp hearts for the chia sometimes.
For anyone tempted to make this, make sure you soak the chia seeds for a few hours first. They're so thirsty for water they can cause some awful bowel problems otherwise.