Will the sleeve or bypass make worse my gas and bloating from possible IBS, endometriosis and/or fibromyalgia?

Both gastric sleeve and bypass surgeries can potentially affect gas and bloating, but the impact varies by procedure and individual factors.
The gastric sleeve is less likely to worsen gas and bloating because it leaves your digestive system intact, though some people may notice mild changes in how their body processes certain foods. With a bypass, gas and bloating can sometimes increase due to malabsorption or food intolerance caused by the rerouting of the digestive tract.
Given your history of IBS-like symptoms, endometriosis, and fibromyalgia, the sleeve might be a better option as it’s generally less disruptive to digestion. However, dietary changes required after either surgery, such as eating smaller meals and avoiding trigger foods, may help manage gas and bloating.

Hello, I hope you are well. A gastric sleeve does not cause malabsoption or any alteration in intestinal motility, hence it will not interfere with your IBS or other conditions. In fact, it should be beneficial as weight loss has been linked to to improve conditions such as IBS.

Neither of these surgeries should worsen any of the issues you have mentioned, and could actually help.  Because you will be eating less, you may feel less of the gas and bloating issues.  You will want to choose non-inflammatory foods, focus on a high protein diet, and if you have endometriosis, stay say from soy products.  I would suggest you consider the Gastric Sleeve surgery since you will be better able to absorb the nutrients from food, and use a good bariatric supplement for life per the ASMBS guidelines for all post surgery patients.