Practically everyone - omni, vegan, or anyone else - needs to substitute B12 fyi as even meat does not contain enough of it. Take a supplement a day and you're golden
Additionally, rather anecdotal evidence, a lot of vegan reddit users also claimed to have better erections iirc. From personal experience, I can support that claim too.
It would make sense, though, since vegan diets have a positive effect on your cardiovascular system, directly leading to less clogged arteries and better blood flow.