It may exist (with a loose term of exist) but they are all mostly garbage. There's still plenty opportunity to make non-garbage version of things that already exist

This is technically true but also a bit naive. Established incumbents are very difficult to dislodge with merely a better version of their products. This becomes more true the larger the product and the average customer size. A good example is QuickBooks, which is a really janky accounting/bookkeeping software that is almost universally hated, but newer and better solutions haven't been able to capture much market share from it.

It’s hard to actually build a better QuickBooks because to build a better QuickBooks you need 1000+ integrations that each took hundreds of man hours to build.

They are not garbage, they are just deeply integrated where a newcomer thinks there is better way to do this but no gurantees you can make it better