Due to "anti-features" introduced unilaterally by some people from FDroid community, it is not possible to find Organic Maps using the search in FDroid client without tinkering with its settings first:

GitLab

Apps flagged with TetheredNet are not displayed by default (#3347) · Issues · F-Droid / Data · GitLab

I'm unable to find Organic Maps app https://f-droid.org/packages/app.organicmaps/ using search box:

By default, it is possible to find apps with ads, with tracking, with non-free network services, dependencies and assets, apps without source code and with known vulnerabilities. But it is not possible to find Organic Maps, an open-source app without ads and tracking.