Is it possible to allow sideloading and keep users safe?

What about making side loading require some moderate level of technical sophistication? Like connecting to the phone over usb and having to manually type some long shell commands, or exit vim, or write a compiling c program, or some other layman proof filter to activate installing outside apps. I feel like grandma would be too intmimidated by this (good), making it too frustrating for even the most determine scammer to explain, no matter how desperate they are for her social security checks. Have it be done in the bootloader so you can't follow these instructions while on the phone, and require physical interactivity with the device (can't be automated over usb). Regardless, this policy is an unacceptable infringement on digital freedom by google.

I believe this is already the case. You can purchase phones that may be bootloader unlocked, allowing custom firmware to be installed. This enables a tech-savvy user to sideload anything they like.

Closed drivers need Android userspace -> Android panics or otherwise refuses to function if it decides it's SE Linux policy is compromised -> you still don't have control over the device.

And we're back to "just break into the thing you've already paid for." Nope. Go away. No more smartphone crap.

If you install custom firmware, you can control the SELinux policy that is configured and enforced by that firmware.

Even if it requires equipment, if people want it, someone will sell doing it.

If there’s a real downside, they’ll be affected.

Ffs. Now we're requiring the aspiring tech user to develop fluency with not just applied cryptography, but SELinux?

Tech industry has completely lost the goddamn plot. Or more specifically, is doing everything it can to make it nigh impossible for the average user to navigate the info asymmetry to actually use the hardware they paid for.