We had a similar situation with an old internal door that had this weird obscure glass panel from the 80s. Kids played football in the hallway and put a crack right through it. Frame was non standard so off the shelf replacements were out. Found a company that does custom glass cuts, link: glazier Hillingdon and they measured the existing panel and matched the thickness perfectly. They even advised on toughened glass so it can take a bit more abuse. Took about a week but the new panel fits like it was made for the door. Not trying to sell you anything.