There is nothing preventing your ISP from providing DoH itself. Firefox (currently) does not use your ISPs settings by default (which imo is the correct move fo

There is nothing preventing your ISP from providing DoH itself. Firefox (currently) does not use your ISPs settings by default (which imo is the correct move for now), but Chrome will use your ISP/router's DoH settings if it provides DoH. There is nothing about DoH that forces you to use a single company.