You can still have plant based jello and gummies.

An elimination diet is the best way to find out if you have any particular trigger foods, this is the point of the low-fodmap diet. You're not supposed to stay on it for life(it's really not good for you long term), just long enough to figure out what's causing your personal issues, because everyone is different. Once you're on the elimination diet your symptoms won't disappear as your gut needs time to heal, however there should be a noticeable increase in discomfort/symptoms when you reintroduce a trigger food, therefore you need to eliminate that food specifically until your gut is healed. My functional medicine practitioner suggested this could take 6-18months, after which I might be able to enjoy trigger foods in small quantities. I've been listening to the ZOE health podcast, all about gut health/microbiome, to get ideas for food swaps I can make that my guts will appreciate 😊

The first important thing is that Fodmap is a process and you will likely integrate foods back into your diet. Would recommend being mindful about many laxatives as I built up a severe tolerance and none of them work for me now. Would recommend trying food-based changes like psyllium husk. I am yet to find a complete solution tho.