If I understand your question correctly @themagus I can share the following:

Things that improve the gut microbiome:

• eating a wide variety of veggies (raw and cooked are both beneficial in different ways- i.e. do both)
• eating a wide variety of fruits
• eating Omega 3 rich seeds (chia, hemp and flax)
• eating a variety of other nuts and seeds
• eating a variety of legumes (well cooked)
• eating mushrooms (cooked)
• adding herbs and spices to food
• eating fermented foods
• eating wholegrains

(Note: if someone hasn't been eating these ever/for a long time, they may need to be introduced very slowly)

More things that improve the gut microbiome:

• reducing & managing our stress well
• regular enjoyable movement/exercise
• connecting with loved ones
• being outside/ in nature/ with pets
• intermittent fasting (having a break of 13/14/15 hours between dinner and breakfast)
• chewing our food well
• being relaxed/calm when eating

Things that harm the gut microbiome:

• exposure to antibiotics (directly and through food consumed)
• eating a lack of diversity of plant foods
• eating fried foods
• eating refined sugars
• eating animal products (meat, dairy, eggs) - the more we eat, the worse it is
• eating processed foods
• exposure to chemicals and other toxins
• alcohol consumption - the more we drink, the worse it is
• stress (mental, emotional - which both cause physical)

As I share these lists @themagus I'm hoping this is what you were after. AND let me say this (as it can be a bit overwhelming at first if this is all new information):

Small changes can make big impacts on our gut health
AND
we don't need to be perfect.

I've chosen to focus on increasing my plant food variety. This gives me a focus on what I'm ADDING (rather than what I'm missing out on) and I've turned it into a game.

If you meant something different by your question, please feel free to ask me again a different way. Hope that helps!