“All” you need to do is reflash your phone and reinstall Android/Chromium (soon to be renamed Android).
Since you are not a certified supplier, the checking is not activated.
On Chromebooks the setting will be on, since they are used in schools, but since it has a terminal you can remove the block, it won’t be simple, probably terminal commands and changing configuration files, but it won’t be impossible.
You can’t sideload in Linux.
“All” you need to do is reflash your phone and reinstall Android/Chromium (soon to be renamed Android). Since you are not a certified supplier, the checking is not activated.
On Chromebooks the setting will be on, since they are used in schools, but since it has a terminal you can remove the block, it won’t be simple, probably terminal commands and changing configuration files, but it won’t be impossible.