GrapheneOS, a privacy and security-focused Android-based operating system, has posted a series of tweets on X suggesting that Android should introduce frequent auto-reboots to make it harder for forensic software vendors to exploit firmware flaws and spy on the users.
They are not hard to acquire, and they only have an “unreasonable price” if they are recent models.
You won’t have any trouble finding a second-hand Pixel 5.
I recently bought a Pixel 4a at 120€ / 131$
Graphene OS drops support for devices pretty soon after Google does. It’s not a good idea to buy anything before Pixel 6 to run Graphene OS right now (see https://grapheneos.org/faq#supported-devices)
This will get better going forward since Google is supporting the Pixel phones for much longer (5 years for the Pixel 6/6a onward, 7 years for the newest devices).