UPF is not inherently bad. Some UPFs (Pasta, wholemeal bread, baked beans, probiotic yoghurts, wheat biscuit cereals), are actually good for you.
The problem is that UPFs come from manufacturers who are trying to get you to buy more of their product, by playing tricks with the brain's response to it.
There are food labs where people are having their brain scanned while they sip different soda formulations, tobacco companies buying food companies to apply their research methodologies, and people figuring out packaging noises and shapes in order to make your old/slow brain excited at the crap you're about to eat (the pringles can is hard to use on purpose, for example). This is all symptomatic of a global food industry that needs you to buy more food, so needs you to consume more food, regardless of nutritional impact.
I recommend reading Chris van Tulleken's book and watching (if you can) the documentaries he made on the subject.
Yes, the Brazilian paper that started all this said "UPF is harming the health of the nation", but the root cause was not UPF processes, it was food industry processes that often require them to produce UPF.
It isn't the UP that makes the F bad, it's that some profitable but bad F needs UP to be viable.
It is therefore perfectly possible for meat substitutes to be UPF and healthy, just as some other UPFs are healthy. In fact, arguably they need to be both to survive.
I am current reading the book you mentioned which is why I made this comment.
But the less processed the better. And eating something else is probably better still.
I feel the UPF "debate" is just an appeal to nature, and calorie/nutrient density should be what we fixate on.
As much as the same can be said about plants.
It's why the debate rarely exits the semantic stage into the empirical stage of argument where we look at the human health outcome data on supposedly scary chemicals.
Meanwhile, we also have data on not-so-processed foods that are bad for us, and the level of processing did nothing to spare us the negative health impact.
If you wouldn't mind reviewing https://news.ycombinator.com/newsguidelines.html and taking the intended spirit of the site more to heart, we'd be grateful.
The only thing in that list that I agree with is Yogurt. Sure, if you live in Europe where they've banned some of the more harmful ingredients and processes and you are taking about very limited quantities, maybe they are not so bad for you but that just puts in the same league as wine or beer.
(the shelf-stable varieties are often ultraprocessed though, and are less healthy than the non ultra-processed ones)