Once again, this is the point.
> it doesn't imply you oppose the freedom to run whatever code you want
But it does.
Let's first look at what's good about "intended experience" & possible legitimate reasons to have a differentiation between "vendor-approved" 3rd-party apps & non-"vendor-approved" 3rd-party apps.
The connotation of an "intended experience" is that the experience is supported by the OS vendor. If you have issues with your experience, these are issues that can be reported & the OS vendor will endeavor to fix. Leaving aside the fact that Google has no user support to speak of, even if they did, this isn't something they would every offer for 3rd-party Play Store apps regardless. So 3rd-party Play Store apps are not doing anything for users to provide them with an "intended experience" that isn't equally available sideloading.
The only other legitimate reason to have a differentiation would be to ensure the user doesn't install malware. Play Protect currently does this with sideloaded apps, so once again there is no difference in the "intended experience" from the user's perspective.
If there are no legitimate reasons to differentiate the experiences, the only reasonable conclusion remaining is that they're differentiates to dissuade user freedom.