This website gets more hits from people looking for information and opinions about vouchers in schools than another website I run, even if I publish a great article about school choice over on that site. That's because this is a niche website, and it has a lot of closely-related articles. There are some positives for websites to focus on a niche, including easier indexing by search engines, a more focused user experience, and money. The money comes from the fact that niche websites (those that get more hits than this one) can make money from ads on the site, and those ads can be very targeted. Niche schools (charter, magnet, specialty, etc.), are similar to niche websites, and there are some positives.
A niche school can have a specific focus. The parents chose the school based on a certain philosophy, and a STEM school isn't going to feel pressure to offer ten foreign languages. That's why new schools should be more focused than "college prep," since true college prep would focus on a very broad liberal arts education. If your focus is on teaching the writing of code, and you've partnered with local businesses, and students are learning the actual process, then you can probably skip the expenses of a bunch of new science labs. With limited resources, a school that can focus will be able to come out ahead in the niche.
The niche needs to be valuable to parents and students. When I search on the internet for a video about changing my car's alternator, I'm looking for a very specific video or tutorial that deals with my car. A video about what an alternator does or how to change one on a Yugo won't help me. It's the same thing with niches. If your niche is fairly useless to students or parents, then you're not going to get the best results in searches and desire to attend the school. Back in my hometown, Boys Tech eventually became Tech, eventually became a neighborhood school, eventually needed to get students to pass all tests, and eventually only offered a true industrial arts education to those who sought it out. The whole idea of graduating high school with a real skill got watered down by the need to pass all the required tests and serve a larger population of students. A niche school needs to have the ability to be exclusive rather than all-inclusive. If your kid has no interest in the arts but wants to attend a school that focuses on the arts because it's highly-rated, then it's not a good match, but that's what happens in a large school district trying to find seats for kids.
Location absolutely matters for charter schools or private schools that might have a niche. While it might be hopeful to create a "college prep" school in an area with lower income, it might make more sense for that school to teach skills that make a student employable without a college degree. An environmental school might not be a hit in a very conservative area of town. Since busing for charter schools generally doesn't exist, it's best to match the niche to the location. In some cases, you might have to alter your focus a bit because of the clientele. For example, there are some Lutheran schools in locations that don't have very many Lutherans. These schools might focus on being "Christ-centered" or "loving" rather than specifically Lutheran.
Proof of concept will help parents to decide on your school. You need to have an outward-facing website that demonstrates your achievements as a school. Not an app or a login area for students and parents. The website should show results. Obviously, if your test scores don't outperform local public schools, then leave them off the site, but you can absolutely show how the students are affected by being part of the niche you've chosen. If you are a STEM school, then photos of students in science labs is a must. If you have a religious school, articles about the latest chapel service would be useful. You don't need to demonstrate that students are getting an hour of code at your French Immersion school if you don't have articles and photos of kids learning in French. Just like I don't write articles about my favorite recipes on this website, you don't want to muddy the message of your school.
Adjusting to market trends can be useful to your school niche. Sure, STEM is all the rage right now, but if employers start discovering that kids who are fluent in STEM tend to have lower creativity quotients, then make your school a CreativeSTEM school. Your English and arts teachers can help with the transformation. Also, I don't know if that's a thing. The point is that no one is telling your charter school that it can't ever adapt. Probably even Montessori or Waldorf schools can adjust to trends. And if they don't (and you do), then good news for you.
Charter schools, magnet schools, and private schools all have a place in our country right now, but it's about more than just fighting for vouchers or tax money. If your school can continue to prove that the investment is working, then the system will adapt to you, and people will want to keep investing. Parents will demand opportunities to send their kids to your schools. Taxpayers and politicians will see the benefits. Even the teachers might want to leave their bureaucratic public school jobs for a chance to teach in new and exciting ways.