I own a 30x30 similar ws28xx matrix, it was nice, but too slow on single pin, you really need to mod to run in parallel. Raywoo has just started making a version in apa102, which is lovely and fast in comparison, though sadly is very much a rectangle not a square, despite what dimensions the website lists it’s actually closer to 50cm by 60cm (from memory. I can double check size of anyone is interested)
@Will_Tatam sure it’s not going to be fast, but after you buy this you simply cut the trace/unsolder in the right places and turn it into a parallel array like Yves and I did. Example: http://marc.merlins.org/perso/arduino/post_2018-07-30_Building-a-64x64-Neopixel-Neomatrix-4096-pixels-running-NeoMatrix-FastLED-IR.html
I’m just pointing out that it took way too long to do myself and that it seems awesome to be able to buy it pre-made.
@Will_Tatam I’m not disagreeing with you, a full matrix is better for sure. But even 32x32 pre-made is hard to find, if at all, and even harder if you want a specific pitch (i.e. space between LEDs).
So for now some people have made their own with individual strips, or they have bought a lot of 16x16 matrices and put them together. The pre-made matrices are usually 1cm pitch aka P10