more concretely WRT veganism, I've long been sympathetic to the cause, for ethical and environmental reasons, and in a much broader perspective than "what do I eat", but "how do I favor behaviors, mine and others', that treat sentient beings well, rather than those that mistreat us?" (I include myself and other humans among sentient beings that should not be exploited, which makes going all-in a lot more complicated while living in a capitalist society)
other very particular complicating factors, when it comes to food specifically: most of my immediate family needs to eat gluten-free, and most of the time I join them in solidarity, and that in itself reduces brutally the pool of available choices, especially for someone who couldn't cook. there's something in chicken eggs that I need to eat regularly, otherwise I slowly sink into depression without noticing before it's too late, which makes it very hard to experiment with replacements or even to find out what nutrient it is that keeps me functional.
but none of these difficulties change how I feel about the lack of ethics in behaviors that bring harm onto sentient beings, or how I oppose them philosophically. however, the strength, the attention, and willpower I have available to fight this specific battle, rather than or in addition to other battles I chose to pick and those that I can't help picking, vary from day to day