MM77PL Unfortunately it is not available within Channels although Melinda_Hu said back in Nov 2020 it was coming soon it still hasn't been put in. I too have been asking for this in respect to education as well especially having a question pop up centre screen to gauge understanding and attention within a class.
I still don't understand how it is functioning perfectly well in the Non-Channel meetings but the second you organise your meetings into channels you lose functions.
I have separate classes all split into separate channels covering the Units being delivered in the class so each unit has its own OneNote and files and calendar for online classes even the Meeting schedule doubles up as lesson plans and attendance registers.
At the moment all we can do is create polls within the chat channel of that meeting not within the meeting itself.