I’ve been trying various things from yogurt, sauerkraut, kimchi and supplements and I haven’t really had success. I must be doing something wrong or too much or not enough idk.

Yes, you’re doing something wrong. Wherever you’re getting your health/microbiome advice from is a poor source. You can find better info here: https://humanmicrobiome.info/faq/

Fermented foods contain non-host-native microbes. Their benefits are hugely oversold. They will not restore your gut microbiome.

Anything that damages the gut microbiome. Ultra-processed foods are one of many things. Antibiotics may be the biggest factor.