[vidarh]

If anything, I can't think of any aspect of mindfulness meditation that requires visualisation. You can do mindfulness meditation with open eyes - one of the popular introductory books (Mindfulness in Plain English) specifically describes mindfulness of breathing on the basis of focusing your vision towards the tip of your nose, and part of the reason is to maintain focus without being distracted by visual input.

Keeping the eyes half-open during meditation is a common way of preventing falling asleep.

I'm utterly unable to visualise for the most part except for one experience that was totally revelatory to me during meditation years ago, which I after learning about aphantasia realises must be what most people experience all the time.. But the inability to get my minds eye to work has never been a hindrance to my meditation as far as I can tell. If anything I do not get distracted by visuals, yet there are more than enough other distractions so I'm mostly happy about that during meditation.