I want to switch with my fairphone 5 to E/OS.
Installation seems to be simple and automated but my question is what is the easiest way to reinstall the apps i use. Doing a backup in some or other way?
Regain your privacy! Adopt /e/OS the deGoogled mobile OS and online services
in general, this is the migration meta help article: Migrate to /e/OS
you could try both “Task 7” items in this guide to get at least the APKs in one go if they’re many: How to Backup and Restore your /e/OS phone
As to install, be careful to read things on relocking very closely, know the security patch date before starting the process.