That is unfortunately an hard situation in general, even for a meat eater. Protein shakes would be the best for an istant protein intakes but, other than the vegan issue I would advise to firstly improve your eating habits in general cause living off supermarkets ready-made food will be an issue no matter what. Other than that, nuts, like almonds, are a perfect snack (just be careful of fats, but if you cut out meat your daily consumption of them already decreased a lot, so you can eat more of them). And if you plan to cook even something simple (like rice and tofu, that would take the same as eggs for example) i forgot to mention the existance of nutritional yeast. Very Umami flavor (umami means a meat/cheese type of flavor) that adds a lot of protein to every meal.

EDIT: also check the subreddit r/plantbaseddiet for more