I think it would be impractical in my ways. Depending on the size, it might be difficult fitting into pockets due to the same length on all sides. A square display is also less than ideal for multimedia purposes, like games and videos. Something lots of people care about.
I’ve used a BlackBerry Passport for a while, which had a perfect 1:1 screen ratio, it was great for documents, ebooks, mails, web browsing, messaging and so on, but really failed when it came to videos.
I am using a Galaxy Fold 4 as my secondary phone which, when opened, also has a rather square-ish screen ratio, and people are disappointed regarding videos, as the large screen only has absolutely minor benefits over a regular slab phone, since black bars take up quite a lot of screen space due to the aspect ratio.