I don't care about deontic constraints as such (that goes for me and my peers). But insofar as many people (especially non-EAs) care about weird deontic things like personal proximity to a cause and hypocrisy, I think advocating veganism is worthwhile, and perhaps has a higher EV than advocating for AW donations.

I doubt many people who aren't vegan donate to AW (beside some EAs, like yourself). A lot of people would clearly prefer to donate lots of money than go vegan, but I think the main thing stopping people from caring about veganism and animal welfare is motivated reasoning; ie, they don't want to admit to themselves that their diet is immoral. And so I'm not sure I'd be able to convince many people that animal welfare matters and that they should donate to it but don't have to go vegan. I could be wrong, and if I am that bodes well because getting lots of people to donate to AW would be great!

As to why I advocate both AW and veganism, see what I wrote above about why I myself am vegan. I think it is communicatively powerful and lends you a certain kind of moral legitimacy that other people (especially non-EAs) tend to care about. The few times I have tried to convince my family members about veganism, they've almost immediately started in on hypocrisy. For example, they would mention things like when I took a bite of my sister's meal that had meat in it, how I used to not be vegan, how I still fly on planes even though I care about the environment, etc. I think all these objections are insane (esp. the one about flying), but they go to show how non-EAs put a lot of emphasis on hypocrisy as something that's morally relevant. 

I think there needs to be a general cultural shift toward caring about animals such that we'd view killing them instrumentally as repulsive in the same way that many people intuitively feel killing humans for the greater good is still wrong (I really liked what you wrote about this here). And to achieve this cultural shift, we probably shouldn't be hypocrites because the people we're trying to convince really don't like being lectured by hypocrites.

I think @Richard Y Chappell🔸 is right. I'd add that lots of my non-EA peers care about hypocrisy (ie, they would be unwilling to entertain arguments in favour of veganism or donating to animal welfare coming from a non-vegan). 

I care a lot about spreading the cause of veganism (and effective altruism more generally), and I think that by eating vegan I hold a certain amount of moral legitimacy in the eyes of others that I don't want to give up because it might help me convince them about animal welfare or EA one day. (Being vegan also provides some reflective moral legitimacy or satisfaction to the irrational part of me that also cares about hypocrisy.)