How to name a group text where some members do not have iphones?

Despite what the support document says, if you have iOS 17, you can name even a mixed group on your iPhone. I have tested this. However, only you will see that name. It's up to the other people to name a group on their phone.

If you want to have a group chat where everyone sees a name and an icon, you'll need a dedicate group messaging app such as GroupMe.

According to the 'related article' above your question here: There

is No way to Name the group ~ IF that contains SMS/MMS users.

Name a group text message on your iPhone, iPad, or iPod touch - Apple Support

//support.apple.com/en-us/HT211301

The Change Name and Photo option is in 'blue text' under the group icons

and names of the people on the thread:

"Remember, you can name group iMessages ~ but not SMS/MMS group messages."

"To name a group text message, everyone needs to be using an iPhone, iPad, or iPod touch."

[You can name a group iMessage as long as everyone is using an Apple device.]

Certain instructions are required ~ as these two message services differ with implementation.

+You can’t name SMS/MMS group messages or iMessage conversations with just one person.