Ladies - great topic! I have a ‘freelax’ (sometimes sold as ‘pstyle’ I believe) and I love, love, love it!
Yes it does take a bit of practice - mostly mentally, but I have used mine for the past 10+ years - through 2 Caminos, Everest Base Camp trip, various other holidays, but also while working (~2 years) in uniform in a “3rd world country - because it was more sanitary than the bathrooms), and even at home working or hiking in the woods. (I am 61)
I carry it, with wipes in a little breathable bag clipped to my pack - a little soap and water at night and Voila!
As to peeing with zippered pants, we’ll I lower them a bit, bend forward a little for ease of flow, do my business - and don’t even take my pack off!
….Never leave home without it and… did I say I love it!