No bridal party, can i still ask family members what to wear?

If I wasn't in my brother's wedding party, and he asked me to wear something specific to his wedding, I'd probably be okay with it as long as it was pretty general. Something like "earth tones" but not as specific as "chiffon, red, short" if that makes sense. We didn't dictate what any family wore and our pictures didn't look tacky at all.

I instructed my family to wear items similar to the colors in the bouquets but not anything specific. And same general for the men "Please wear a suit and tie!"

I think if they reach out to you and ask, it's ok to give your opinion. If they don't ask you, then they probably have an idea of what they are wearing already and it would probably be rude to dictate what you want that to be. In my experience, this has always worked out in the end anyways. People typically wear neutrals to weddings anyways.

My cousin and her now husband didn't have bridal parties. They asked family to wear a shade of yellow, light blue, or navy for pictures. I think as long as it's general it's alright

IMO it depends. I wasn't going to ask many people to wear a certain color, but then people kept asking me. So anyone who wanted to coordinate with the wedding is wearing colors of gray, shades of purple, and browns. If no one asked me what color to wear then they will wear whatever.

I think if they know that you're honoring them and having them do special readings and speeches in lieu of having a bridal party, then it's totally fine to ask them if they'd feel comfortable wearing some sort of coordination.