I need help marketing my service

I built an event ticketing service. Just like on eventbrite, etc people can create events and receive payments by selling tickets.

The service can be found at https://einladung.app (its in german language only for now)

The service is built and is ready for customers, only problem is I have none.

My best idea to market it is by looking for local sport clubs all around germany and send an email to each one. They could use it for events they organize. Other potential customers are organizers of small local street festivals, flea markets, nightclub owners, universities or any kind of local communities. I would look for each city / area individually and search for any of these prospects and send them an email.

My biggest mistake in this journey so far, was not validating my idea before building it. It sure does great on my portfolio but I don't know if any of these people would even use such a service.

Anyways, I have sent 2 different kinds of email so far

1. Telling them im a university student, starting my first startup and asking them to take part in a survey. this would help me analyze them and understand them better. After they did the survey I could follow up with advertising my product, asking if its something they could use.

2. really short and direct email, telling what I build, for what they could use it, sharing the URL and if they are interested in something like this.

Other ideas of marketing are printing 10.000 flyers and distribute them in my city in regular peoples letter boxes.
Or asking my university if I could put these flyers in their goodie bags, which get handed out in march for new students.
Another option would be google ads but I don't know how effective this would be.

I think if I get like 10-20 users the snowball could start rolling a little bit, as people who attend events get exposed to it and see use cases for the service and word of mouth could start, getting me more customers.

Any feedback?