What software do you use for work (not consumer software), that doesnt have any good options for the category it’s trying to solve?
Which means making it possible for customers to automatically transfer all the data they have already created with the old software to the new software with zero loss.
It also means convincing the customer that the cost of learning the new software is worth it.
And it means convincing the customer that having to deal with your brand new set of bugs, instead of the old set of bugs they have already learned how to work around or fix, is worth it.
In other words, you need world class sales skills way more than you need developer skills.
From my understanding, the more "serious" the industry is, the less cool new alternatives will be there. As an example, software for cashiers in a lot of countries is still running on windows 95, just because it was once developed and then, nobody bothered to update it, think of new features, etc. Public transportation systems, especially ticketing, if the country/city won't invest in upgrading, it won't happen. You can also think about more hardcore industries (chemistry, machinery, etc.).
But it's incredibly hard to get into these things, "don't fix what's not broken" is a pretty good reason for rejecting new ideas, but of course it all depends on your location, ability, expertise and all these good things.
I'm sorry for a very broad response, hopefully it can give you some thoughts, sorry if not.