Don’t the impossible/beyond meats still have a higher environmental impact than poultry?

I can't seem to find any information about this, do you have a source?

At least for CO2 emissions it looks like they're roughly on par with each other. Impossible Foods claims a 3.5 kg CO2-eqv. per kg product[1]. For chicken meat, the emissions depend a lot on how and where they're raised, but according to this UN report[2] it's roughly 2.7-8 with an average of ~5.4. It's a bit lower for eggs at 2-5 with an average of ~3.7.

EDIT: This study[3] has a more detailed breakdown which roughly matches the numbers from the UN report. For meat: 2.3-12, average 5.7, median 4.3. For eggs: 2.6-7.6, average 4.2, median 3.8

[1] https://impossiblefoods.com/mission/lca-update-2019/

[2] http://www.fao.org/3/i3460e/i3460e.pdf

[3] https://science.sciencemag.org/content/360/6392/987

Where do you get enough protein to maintain muscle integrity ?

It’s generally a myth that vegans don’t get enough protein. There are tons of vegan based proteins and Americans are obsessed with maximizing protein intake where you really don’t need to.

There’s plenty of vegan athletes and weight lifters. If they don’t have issues as an elite athlete I doubt the average person will have an issue.

Vegan for 20+ years (now 40). I've never had any protein deficiency or any other nutrition related health problems. I weight lift so I take a scoop or 2 of brown rice/pea/soy protein which gets me to what any muscle gain diet guidelines recommend.

I have been eating similarly to the parent poster recently (trying to avoid meat and dairy as much as possible). The three major sources of protein I use now are black beans, kidney beans, peanut butter, and tofu. I also sometimes eat tempeh which can be good in the right contexts.

It takes some effort, but it's fairly straightforward if you can find ways to substitute it into your daily meals. I like taking an existing meal and just replacing the animal products from it. One example I like is a chicken curry wrap. It's just chicken mixed with mayo, curry powder, celery and onions, all stuffed into a wrap. I've substituted a lightly fried tofu in place of the chicken and a vegan mayo instead.

I'm not a vegan but beans and rice go a long way.

Beans also have tons of fiber. You can easily get 20 grams of mostly soluble fiber from a bowl of beans.