Unfortunately there’s no option to move the next button at the moment.
So, to move the button, you can try it yourself, or reach out to us for help!
To try yourself, you can add CSS to your theme (usually a theme.css or style.css file) which can move the buttons below the products on the step, rather than fixed at the bottom of the screen. To accomplish this, try adding the below:
#bxp-bldr-bottom-wizard {position:initial !important;}