Google has news on what you will need to do for still being able to sideload apps:

* enable developer options
* confirm that you are not tricked
* restart phone and re-authenticate
* wait one day
* confirm with biometrics that you know what you are doing
* decide if you only want unrestricted installs for 1 week or forever
* confirm that you accept the risks
* enjoy the few apps that still have developers motivated to develop for a user-base willing to put up with this

https://goo.gle/advance-flow

They even have a video up where they try to make this all sound nice and positive:
@grote i want to stop using inoperative systems like android or ios, that's it
@oatrapado @grote Europeans might come to the rescue in the coming years with creations like FairPhone and Jolla Phone. Maybe if the donations start flooding in, Pine64 might be convinced to put more effort into the PinePhone.
@Frenezul0_o @grote those chinese/european phones are just obsolete and overprized, pinephone another archeological piece at a high price.
@oatrapado
Let's be fair its a pocket tablet that can also make phone calls, and the calls are often not the primary purpose any longer
@Frenezul0_o @grote
@oatrapado @Frenezul0_o @grote at this point, freedom is worth paying for slower hardware
@grote maybe bro should build an advanced flow for keeping the microphone a consistent distance from his mouth
ComicitΓ  all'Italiana: L'allenanore nel pallone - Mi avete preso per un coglione

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@grote Yeah, "committed to openness", what an ugly lie.

And "one time 24 hour wait" ... I bet that will be a lie, too. I'm pretty sure this will hit me more than once :-(.

Google is evil.
@grote
Not watching it. Thank you

@grote ok, what's freaking funny is this act is required UPON TURNING ON DEVELOPER MODE. Imagine if you need to do this every time you need to turn off developer mode because some banking apps check for developer mode. THIS IS HORRIBLE.

If you want to limit app installation, don't limit developer mode. Adb is borderline not ok but still, something else. Maybe this is only required if you need to enable app install from untrusted sources apk.

@grote "For power users, we think this is a fair trade-off." Now go and ask the power users.
@grote he lost me first when calling it that made up term instead of installing. Then lost me again by holding a microphone in his fingers in a video.... I find this trend so distracting and silly lol.

@luboganev @grote Lol, I was more confused why that guy was wearing two watches ... πŸ˜†

At least the video didn't have this disturbing happy-background-music melody.

@grote Gaslight, Gatekeep, Girldroid

@grote wow that wording feels so much bullshitty

removing all the bullshit would probably leave you with β€œβ€¦ a … a … a …” removing also spaces would summarise my feelings about this: aaaaaaaaaaaaaaaaaaaaaaa!