Have you tried veggies with a dip? Do they like ranch dressing or peanut butter dips? Frozen peas might be a hit even if they won't eat cooked. Would they drink smoothies made with pumpkin or anything like that? Or try blending combos(now don't ask me what they'd be) of fruits and mild tasting veggies for frozen pops. Blending veggies into sauces or soups, meat loaves, etc. Course if they're like most of my dcks they wouldn't eat those either!
My own used to be so picky when they were little and I tried all the tricks out there back then. They started eating veggies when they were good and ready. Now they're more adventurous than I am in their eating.
Course they're adults.
I have a couple dcks who would have as many veggies as I let them, then 2 toddlers who eat some but not many and an almost 3 yo who doesn't eat any veggies. I figure if they're getting plenty of fruits, esp. the 'better for you' fruits then they're probably doing okay.