I don’t think they will prohibit side loading. This will cause serious issues to developers, and other professionals.

Like, I cannot use the X tool from Github, just because the Y developer refuses to publish it in an organized store?

This also applies to Windows. What prevents a user from downloading a Firefox fork that does not properly implement age verification?

Since it is impossible to implement on Linux, it may just be flagged as adult-only software.

But, there is still hope. What if Snaps and Flatpaks get properly flagged, allowing Ubuntu and/or Fedora to be legal?

Maybe you can

Sure, in many cases the dev’s computer is powerful enough to handle that.

However:

• The more the dependencies, the more likely it is to pull-off a supply chain attack. Any of those thousands modules can be compromised and infect either the user or the developer.
• Not all computers are optimized for working with so many tiny files. Have you ever worked in a company that uses McAfee Antivirus? Even Defender can be a massive performance hit in some cases.