Being vegan is easy for someone who does hard physical work, so they have to eat more than 3000 kcal per day. In that case, eating enough proteins that come from plant sources will still leave enough in the energy budget to also eat other food, for a complete diet.
On the other hand, if you have a sedentary lifestyle, working in the front of a computer, it is impossible to eat enough protein without eating too many calories.
There are plant protein extracts, but those are at least 3 to 5 times more expensive than cheap animal protein, e.g. chicken breast.
I have eaten for 4 years only plant-based proteins, but to satisfy simultaneously 3 constraints, enough proteins, not so many calories as to cause weight gain and price no greater than when eating chicken meat, in Europe where I live there was only 1 solution, with no alternatives.
The solution was to extract at home gluten from wheat flour, to supplement the proteins provided by lentils or other legumes. Any plant-based product that I could buy for enough protein would have been more expensive than chicken meat.
Extracting gluten, which is done by washing dough with abundant water, works. However it requires much time and much water. Extracting pure gluten requires so much water and so much time that I never did this regularly. I was typically removing around 75% of the starch from wheat flour, and with the result I was baking a bread that had about 50% to 60% protein content.
Besides wasting a lot of water and time every day, this procedure had the additional disadvantage that the amount of calories provided by eating enough protein was still rather large. This limited severely the possible menus, e.g. any starchy vegetables, e.g. potatoes or sweet potatoes or rice, and any starchy fruits, e.g. bananas, had to be forbidden. I gain weight extremely easily if I exceed my allowable daily energy intake.
These inconveniences have made me eventually abandon this approach. While I still eat mostly vegan food, I also use in cooking some whey protein concentrate, which can increase enough the protein content of plant-based food.
There already exists a technology for making whey protein concentrate otherwise than by the filtration of milk, i.e. by extracting it from a culture of genetically-modified Trichoderma fungus. I hope that this technology will become viable commercially, because unlike with fake meat produced from cell cultures, it is certain that with such a fungal culture one can make proteins less costly than by growing chicken or other domestic animals.
The availability of such a protein powder would solve completely the problem of vegan food for me. I do not need fake meat.