It’s can feel awkward, but it’s okay to speak over them for a simple “good morning” and maybe a wave. Youre not taking over the conversation.
I know for myself, it can be hard because I don’t want to interrupt, but I have to remind myself that it’s okay sometimes. I don’t need to wait for them to let me speak.
Just don’t be a dick and take over the conversation. Say good morning and let them go back to what they were talking about.