Columnar fruit trees

I just came across an advertisement on Instagram for these, and went onto the website. Anybody got any experience of growing these types of fruit trees, they sound very intriguing to me.

https://www.mylittletree.co.uk/mylittlet...w5TOYI0wvk

I hope this link works.

I think the two words that appear to be missing are 'Self fertile'.

I may be wrong, but if you don't have the pollinators to go with them (especially apples which sometimes are triploid and require three pollinators) you may not get any fruit. I haven't fully read the blurb, but don't think some of these cultivars are self fertile?