Online conferencing platforms are not knew. One of the oldest is GoToWebinar
The problem with this program is accessibility or rather the lack of accessibility specially of the windows version. I have reached a point where if I saw that an organizer would be using GoToWebinar, I would not join that conference.
I recently took another look at the platform. The mobile app at least on android is somewhat usable but I prefer using my desktop. I tried the web application which worked quite well. It is still not as accessible as Microsoft Teams or zoom but if you use the HTML 5 client, then you can at least raise your hand, ask questions and perhaps mute and unmute audio.
The way you invoke the HTML 5 client is as follows.
GoToWebinar sends you a joining link. This link is usually specific to you. At the end of the link, add the following text.

?clientType=html5

Google chrome or chromium are the best browsers for this software though firefox is also supported. If you want to read more details, please see the following article.

How do I join a webinar from a browser?

The article gives one way of appending the additional parameter to the link. If you like, you can paste the link into a program like windows note pad and then after appending the parameter, paste the entire link into the browwser.

When using NVDA, I was also able to ask questions. I got focus to the link called “questions” and hit enter on it. Nothing happened but I explored the screen and found an edit box almost at the bottom of the page. This is a regular edit box where I could enter text and hit send to submit my questions to the organizers.

I am happy about this improvement in accessibility. If I ever host a webinar by this platform, I’ll update this post with the hosting experience.