Obviously gender nonconforming people have different underwear needs. Where are your favorite places to shop? I tried buying some mens boxer briefs at the dollar general(next door to my therapist), and it was like they were too loose and too tight at the same time, and the fabric felt terrible, and my rubber D fell out the leg while I was cooking mac and cheese, which, you know, is less than ideal.
Eh, Walmart, JCPenneys...doesn't matter to me. As long as I can find a nice pack of boxer briefs or boxers, I'm fine. I got some amazing things at the latter for pretty great prices. Making a harness to keep everything in place was pretty easy. If I was just packing with a simple packer, then you can make a simple pouch by sewing the front fly closed and then you can slip your packer through the back and secure the inside with some velcro to keep it in place.
I wear panties all the time now, even under boy clothes. I buy mine through Amazon. Finding the right size can be challenging, but more often than not, I get some that are a bit too small, so my wife steals them and no harm done. Amazon is wonderful.
You could get a jock strap. They work well. You could put it where the cup normally goes or you don't have to, they keep them nice and secure and IMO are very comfy when packing. That said, Making a harness is very easy. uppercasechase on YT does a video on how to make them. Just look up "HOW TO: DIY Harness." If the sewing part is still too much, superglue would probably work fine xD If it's the comfort of the underwear that's bugging you though, maybe consider something with nicer fabric. I have furry upper legs so if the hairs get caught up in the fabric it can chafe and that is a rather unpleasant experience. I pack without a harness. I have a heavy STP/packer so I need something that will be secure, have a fly that isn't a pain to use, and be comfortable, of course. My favourite cheap ones so far are Everlast trunks. I do like my Jockey boxer-briefs quite a lot as well but they are rather expensive (to me).
Morgana, I agree that amazon is amazing! Ronin, all that sounds really helpful. I'll do some more research about some of that. Thanks!
I shop at target. They have a brand of underwear there that is men's style but for female shaped bodies. I don't remember what the brand is called, but I believe the style is called "boyfriend" underwear. I know it's still technically "women's" underwear but it actually makes me feel less dysphoria because it's a boyish style that fits me (men's clothing not fitting me gives me a lot of dysphoria) I hope that helped some