I was at the /e/-foundations forum adviced to search for a fastboot package for Fedora 33. As I further learned by experience. It is better to ask experienced users in here instead of searching the internet for random Linux softwarepackages and downloading them.
The purpose is to reboot and clean my Smartphone so I can get 2FA.
Both adb and fastboot are provided by the package android-tools. The version in F33 should be pretty recent, unfortunately it has not been built for F34 yet.
dnf can conveniently identify which package provides a file of interest, eg.:
$ dnf provides fastboot
android-tools-20180828gitc7815d675-8.fc33.x86_64 : Android platform tools(adb,
: fastboot)
Repo : @System
Matched from:
Provide : fastboot
android-tools-20180828gitc7815d675-8.fc33.x86_64 : Android platform tools(adb,
: fastboot)
Repo : fedora
Matched from:
Provide : fastboot
Thank you fasulia. Will dig into that in a minute 
Is the ADB android package allready a part of Fedora 33. Or do I have to download and install it in my libary ?
This is what confuses me. But as I understand your reply. I do not have to use third party software:
fastboot and adb are sufficient for installation of custom roms to Android Phones.
Using the components of the SDK will give you the latest version of adb and fastboot.
After reading the article. I want to be sure that downloading is opensource and not trackedable.
But as I understood by fasulia. There is the fastboot tool for Android in a package to install included in Fedora.
I just didn’t manage to find download and install it yet.
You can use the Fedora RPMs.
Unless you have specific reason to use the versions come with the SDK.
How can I download from the rpm and install the repo ?
I have no other reason than keep it opensource from trusted developers. And using Gits from same organisation as here.
First of all, we know both adb and fastboot are provided by android-tools, by following @fasulia examples.
Then from your Fedora, you can do a search for this package:
sudo dnf search android-tools
Last metadata expiration check: 2 days, 17:31:09 ago on Sun May 23 16:43:16 2021.
======================================== Name Exactly Matched: android-tools =========================================
android-tools.x86_64 : Android platform tools(adb, fastboot)
If you can find it like above, then you can install it by:
sudo dnf install android-tools .
Thank you Sampson and fasulia. That was easy and worked in few seconds 
[TemplePusher@jonas-bloch-riisgaard ~]$ sudo dnf search android-tools
Installing:
android-tools x86_64 1:30.0.5p1-1.fc33 updates 1.5 M
Install 1 Package
Total 1.5 MB/s | 1.5 MB 00:01
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
Preparing : 1/1
Installing : android-tools-1:30.0.5p1-1.fc33.x86_64 1/1
Running scriptlet: android-tools-1:30.0.5p1-1.fc33.x86_64 1/1
Verifying : android-tools-1:30.0.5p1-1.fc33.x86_64 1/1
Installed:
android-tools-1:30.0.5p1-1.fc33.x86_64
Complete!
[TemplePusher@jonas-bloch-riisgaard ~]$