Samuel McNeil is a young speedcuber from Scotland, in 2023, he received a 21x21 for Christmas and refused to scramble it for many months, eventually he agreed to actually solve his very expensive Christmas present. The solve took place on November 16-17th 2024 and the timelapse has finally been edited and uploaded to YouTube. The 21x21 is currently the largest mass produced cube and I can source you one for around £1250, however, YuXin have announced that they intend to release a 29x29, if they do actually release this, then it will be much bigger than the 21x21, the largest cube anyone has ever actually done a full solve on was a 3D printed 23x23 by Jacob Cubing.
The full solve took 12 hours and 20 minutes, this is far slower than the world record held by AP from Canada of 1 hour and 18 minutes but is still very impressive for a first try by such a young cuber.