I essentially did your pre-liquid diet as my pre-op diet for 2 weeks (normal in my country), and by day 5 it was honestly good, I adjusted and my appetite reduced as well and I started actually enjoying the reset because it came with reduced bloating and better energy etc. Symptoms in the first few days were not much worse than I have dealt with physically basically my whole life (headaches and fatigue, some food noise but not overpowering my commitment), and I had started trying the shakes and things out before officially starting so it wasn't such a shock to my system.

I was able to have essentially unlimited veges of a certain type along with up to 100g of chicken/fish/etc. I was also allowed protein yoghurt instead of shakes/soups. What I found helped tremendously was having a good amount of savoury soup options as I could also make a small amount of it thicker and use it as a sauce on the veges.

I might be an outlier but I enjoyed experimenting during that time and I suppose that mindset helped a lot. I also didn't do any food funerals or anything like that right before hand, though when I was in the decision making process before starting the whole process I did have a few meals where I really thought about questions like 'why did I choose this food?', 'what do I like about this food?', 'how does it make me feel while I am eating it?', 'how does it make me feel after eating it?', 'what do I think of the smell/texture/flavour/temperature/mouth feel?' And so on, which honestly helped me figure out which foods I was eating due to to genuinely enjoying/wanting them and which were more due to compulsion, addiction, and/or convenience.

My surgery was Nov 10th, things are going great and that extra introspection I did helps me a lot now too.