How to find a buyer for (part of) a business

Me and my partner have a business together (located in Germany). We built a booking management software for individual travel agencies (right now in the leisure sports industry such as triathlon camps, swimming camps and so on) and have two paying companies (owned by the partner). We both own 50% of the company and I want to move out of the company due to health related issues. I am the technical founder of the business so with me leaving the company this hole needs to be filled. It is not sure if we will shut down the company or if my partner continues in another scenario (e.g. with an agency filling the gap or an individual). So we are evaluating different options here. What would be the best way to find a new partner with a technical background or even an agency?

Stack:

Ruby on Rails

RSpec (~70% test coverage)

MariaDB

Redis

StimulusJS along with some plain VanillaJS

TailwindCSS

heroku

:edit: formatting