Indeed there is no software limit at the number of videos playing at the same time. The codec matter. H264 is well supported by all GPUs now, HAP codec is handled natively by MadMapper 3.6 and later with better performances. You should give it a try.
What resolution will the videos have ?
On a good desktop PC or a good mac, I can play a bunch (8?) of 4k videos without frame drops. On my MacBook Pro 2018 I can play the equivalent of 10 full HD movies.
If your videos are low resolution (since you show a lot it doesn't have to be high resolution, except if you have 12 projectors
), you could play 100 I suppose.