How important explicit back and next buttons in onboarding?

I am designing on-boarding screen for android mobile app, I was looking at onboarding screens at dribble found that some of designs do not have back and next buttons, just have the dot indicator and skip button. example

How important to have back and next button in an onboarding flow? Is it sufficient to just have a dot indicator with swippable slides and a skip button? If yes how you go about doing accessibility?

Update: In response to comment

In my case info shown in the onboarding slides are important (features, how app works) to new users. User cannot get back to it, if they skipped it, but they will be able to find the more detailed version of same info on the website. And also there is a guide section in the app itself where things are organized under different topics, tapping on a topic item will lead the user to the website where they can learn more the particular topic.