I was thinking on this some more, and another source that I didn't mention was mycoprotein and other fungal proteins. These aren't as common, but you could look for Quorn (note that many, but not all, of their products do contain egg) or Meati. Mushrooms have a good % of calories from protein, but they do tend to be rather expensive so really more of a way to round things out. Nutritional yeast is more of a seasoning than a food per se, but you might get a gram or 2 here and there. I put it on popcorn and mix into some sauces.
There are also some non-wheat grains that I would consider modest sources of protein: oats and quinoa. These aren't heavy hitters and aren't enough on their own but can help fill in the gaps and provide some variety. Oats at least are also very inexpensive.
It's worth mentioning that I specifically avoided introducing myself using the "v-word" (vegan). Although I consider it to be the ideal to strive for, I take "don't let perfect be the enemy of good" to heart and find that discussing a reduction in animal products to be a more approachable goal for many people. I'm not a dietician and won't claim that everyone can make it work without animal proteins, particularly those with multiple allergies, unique requirements, or limitations on what food is actually available to them. From your earlier comment, I agree with your assessment on lab-grown meat and am a huge supporter of these technologies. You should know that lab-grown dairy protein (whey) already exists and is available in commercial products. I have had ice cream and cream cheese using this animal-free dairy protein.
I'm sorry if my previous comment came off a bit aggressive. I think I had misread your intent, but now it is clear that we are on the same page.