@Maker_of_Things you will lose all data that you haven't backed up / that doesn't get saved remotely by the app.
The installation process itself is often only a matter of following instructions to the letter, it can be more or less confusing depending on the phone, and different guides can be better or worse. I'd say you don't need much technical understanding, but you need to be able to follow instructions to use a command line tool.
However, the options don't look great for your phone.
For not-Android, PostmarketOS is the most mature option afaik. It does not support your phone fully: https://wiki.postmarketos.org/wiki/Samsung_Galaxy_A13_(samsung-a13)
For Android-but-without-Samsung's-bullshit, Lineage, /e/ and Graphene are the big options, but those don't support your phone.
https://wiki.lineageos.org/devices/#samsung
https://doc.e.foundation/devices
https://grapheneos.org/faq#supported-devices
You might be able to dig up something unofficial by looking through here: https://xdaforums.com/tags/samsung-galaxy-a13/
But you should expect out of date and incomplete information, especially guides that assume background knowledge that they don't mention. This is the only situation where I'd seriously warn you that an incomplete guide may lead you to do a wrong thing that will break your phone.