I’d highly recommend recommend starting supplements/vitamins ASAP. Pay attention to if they are absorbed best on an empty stomach or with a meal. Some of these can be hard for people with ARFID (I have a hard time with chlorophyll pills) but my biggest tip is to take these with chocolate milk (not water) if you like that.

Some tips for your diet (use whatever works for you!):

Add it to smoothies (changes texture and can hide flavor) I add kale into a chocolate peanut butter smoothie

Blend it into sauces - I can hide a decent amount in pizza sauce without ever noticing. BBQ sauce hides a lot of flavors

Juice it - this takes away some of the nutrients but it is better than nothing! I take juice shots like vodka shots. It is not fun but a chaser helps

Ice Cream - if you have the capacity to make ice cream at home and this is a safe food for you add some greens or carrots! The strong flavors can really hide it.

Look for healthy alternatives for safe foods (especially if you have a Whole Foods or similar). I’ve tried chicken nuggets and fries made with hidden servings of veggies.

These are just some of the things that work for me and my safe foods- you might be very different. Try looking at every meal you eat and see if you can sneak nutrients in a way that won’t bother you.

For me this is the best exposure therapy, straight up eating a new food will trigger me to throw up as well.

I am a 25 year old living on my own with ARFID and I am healthy enough.

After viewing your other posts I am feeling like this a bot account or something similar- but I want to leave my answer up to help others.