The answer depends on how much you want to get better.
The very best thing for you to drink in place of coffee, and the only thing recommended on the strict diet other than certain herbal teas, is pure roasted chicory root. It has some body to it (unlike herbal teas) and is a potent pre-biotic, creating beneficial effects for the good bacteria in your gut. Adding coconut milk to it, if you are that far long in the diet, helps make it feel like coffee. Xylitol, if you have tested that, can sweeten it nicely, or stevia.
You should be drinking nettle leaf tea at some point during the day, regardless of whether you like it or not. It’s very important to the health of your liver.
Depending on how bad your infestation is, and how willing you are to prolong recovery by slowing gut healing, you could try, in what I’d guess is ascending order of potential to derail you:
Teecino or other blends of chicory, roasted barley, etc. You may get reactions to those other ingredients that make you feel crappy and slow down your recovery. If you want to risk it, you could give that a try.
Yerba Mate is an herbal tea that offers some of the caffeine and feel-good effects of coffee. Caffeine is hard on the adrenals and most of us have significant adrenal fatigue as part of our symptoms. But if you were really needing the energy boost and were in danger of getting fired, you could try that.
Cold brewed organic decaf coffee. Google cold brewing. It reduces the acidity of coffee significantly, which is one of its negative effects on the gut.
Again, the only recommended drink is pure chicory. You should really stick with that for the first few months of your treatment.