Pulling together my experience, and what I observe from many others once diagnosed is that often the following happens:
As
@Oldvatr stated replacing sugar based treats has varying results. I would say most are fine with low carb vegetables in place of starches, for meat eaters the proteins are identical. Many struggle with the removal of potatoes and rice.
It is the sweet things that can be a gotcha. "We" have been use to, up to the point of diagnosis, of having sugar based meals for 30 / 40 / 50 years several times a day, when 2 or 3 generations ago, a sweet treat would have been a single orange at Christmas (an anecdote from my wife's Grandad). It is a physical and mental adjustment to then potentially change eating rituals "baked" in. This is when bridging the gap with might be an idea, such as stevia based home made afters in the short term. I believe if a whole food animal based Keto-ish diet is employed, sweet taste preferences automatically shift to savoury.
What I can say with some confidence is that my family have found it impossible to get bored of meat / fish, as there are so many ways to cook; over the Christmas period we were at Steak and Co, where you finish your steak on an individual hot plate, what a taste. When the rest of my party had sweet desserts I had 2 further servings of the best seasoned prawns I have ever had. Similarly last night at Stoke by Nayland Hotel / SPA / Golf Resort in Suffolk, our steaks, chicken and vegetables were delicious - I had a cheese board (with my contraband home made smuggled in seed crackers and nuts - sorry, but these should be offered on the menu (they cater for other diets), the others had an indulgent dessert.
It looks like in the States Keto treats are far more prevalent compared to the UK. There are pros and cons of this, as the "cleanness" of these and the effective replacement with a potentially bad habit with another can be dangerous for results. The medium sweet items I have (for other reasons other than sweet taste) are all of the berries, occasional home ripened plums and cherries when they are not ripe.
Personally I would forget about out of the box so called treats, they spike non-diabetics as well, make your own or choose the likes of berries.