I would have to say that the Ensure and yogurt are a No for bunnies- both are dairy based and in no way natural for a bunny to consume.
The pineapple juice unless it is fresh is not very beneficial. And just adds sugar content.
Metamucil comes in different flavors and some have sugar or artificial sweeteners- so I am really unsure and not familiar with Metamucil at all.
There are 2 flavors of Critical Care- Apple Banana and Regular- the regular is anise (fennel) flavored which does not sound good to me- but bunnies are supposed to like it also.
If you want to try something other than the Critical Care- I would try using pellets, water and or/Pedialyte (will add some sugar but also beneficial electrolytes so it is a fair trade off), and maybe some babyfood that has minimal ingredients that are on the OK list for bunnies.
I mixed Schroeder’s Apple Banana Critical Care with grape Pedialyte- and tried with some baby food also to tempt him to eat. But what I found really made the most difference in his case was being on an appropriate dose of pain meds- when he was in pain he flat out refused to be force fed- he would NOT swallow. But once his pain was under control it made a huge difference in his recovery.
The CC mixed with Grape Pedialyte does still not taste really sugary- I touched my tongue to a spoonful to see to make sure I was not feeding him a “sugar bomb” and it was really quite plain. And I mixed the CC fresh everytime I fed and if the Pedialyte was cold from the necessary refrig I microwaved for a few seconds and then stirred with my finger to make sure it was not too hot before I filled the syringes. If it would burn my finger it would burn his mouth- and microwaves are known to cause hot spots when you heat small amounts of food.