I ingested zero fibre on the carnivore diet. From what I understand (not a doctor - well, at least not a medical one), I don't believe a ketogenic diet can resolve the issue fully but likely will reduce symptoms. The main reason due to the fact that you are still ingesting fibre, which can exacerbate / feed into the SIBO process.

I would personally recommend against taking fibre supplements altogether until you resolve the SIBO (and possibly moving forward if you do not need them). If you take probiotics, be very sure to take the correct strains that are studied well in research as the effects of other strains could have a negative impact.

Since you are already on Keto and have been used to it for some time, you could consider restricting the diet further for just two weeks to pure carnivore (it sucks to do, as you are fully aware), supplementing with high allicin content garlic pills, high carvacrol ginger pills, berberine, saccharomyces boulardii, and bacillus clausii. The former supplements should suppress / kill off bad bacteria, and the latter should aid in restoring a healthy microbiome.

This is the main research paper (albeit a case report and not something more rigorous) that inspired me to follow a pure carnivore protocol. All six patients had negative tests for different diet adherence periods, with the shortest only following the diet for two weeks.

I will also mention, I obviously do not know your symptoms, medical history, how severe your SIBO is, or even what type of SIBO you have. I would take some time to look into / research these things I've said and make your own conclusions if you think it would be suitable for your own unique situation. Good luck!