Luvin eye full, it almost sounds like you know someone that ended their life over size disappointment. I've learned just a little about this issue by reading the forum r/smalldickproblems on Reddit. I was curious about that forum after getting a Peyronies injury and losing a half inch of length and girth. I was someone that hated my average penis size, then lost size to an injury. How ironic......
I'm also heteroflexible and have received penetration with a penis. I'm definitely a size queen as well, but have been surprised by a couple of 5 inch penises that felt very good.
I don't have some life changing advice for men with less than 5 inches, but I have a few pointers. First, my last long-term girlfriend left me for a trans male person that doesn't have a penis. She was a size queen that I used bigger dildos on to give her that full feeling. Her trans male partner swapped his average 5 inch strapon for a very girthy 7.5 incher, and they work things out. A guy with a very small penis can include toys too. I know this saddens or even angers some un-hung guys, but it is true.
There's a movie titled Headwig and the Angry Inch about someone that cuts off most of their penis, then has to make their sex life work out after that while having just a stub.
When it comes down to it, there's multiple ways to still provide penetration. Penetration isn't everything, but it is why most small guys feel doomed. So solving the penetration obstacle makes sense to me.