I keep separate devices and networks. It is not privacy as much as it is purging suggestive content and convenience. I only purchase something when I go looking for it specifically. I never browse or shop as entertainment or for endorphins. Investment apps are all about the stalkerware because it says you are a major target for unnecessary nonsense. Get a tablet and only use it for that junk.
Checking out how to build an OS from scratch is also handy. It can be an interesting low risk way to explore building Gentoo, Arch, or Linux From Scratch.
The main appeal IMO, is that you have microcontroller like input, output, and serial communications already setup in the kernel with access in user space. As long as the kernel is supported by the Rπ foundation, (it is proprietary undocumented hardware that only they can support), you are getting the security updates required to keep the thing online automatically and safely. The best stuff to build is unique stuff for you that uses these aspects. Like make a little bathroom clock with a little TFT LCD display that tells you the local weather. Then set up some RSS feeds for local community stuff you do not want on your main mobile device, like maybe local political activity, library and community center events, concerts, clubs, etc.
For server stuff, I would stick with devices with purpose built hardware. Like, a micro SD card is slow and unreliable, and the lack of nvme is bad. In most cases it is cheaper to use other old devices that already have screens unless you want to share a hardware design that is repeatable, you need something secure to keep online, or you need serial or input/output. Those are the main benefits.
The thing is, the Rπ is what it is. It is the path of least resistance. The software support is approachable and great. The price is cheap. However, the non profit thing is a scam. The Rπ foundation is basically an arm of Broadcom. The Rπ is a chip from a set top TV box with 3/4 of the die unused. Broadcom uses excess fab capacity to make the Rπ chips and sell them at materials cost. This is not charity. It is controlling the grass roots market to make competitive scaling business ventures difficult. This is why Rockchip is not crushing them already. The Rockchip RK3588 chip is fully documented and open source. In this space, there is little to no innovation, it is only about price on ancient trailing fab nodes. This is the ladder to climb that leads to Intel, AMD, Samsung, and Qualcomm. The Rπ is the guy kicking anyone that tries to climb. So… use it for what it is good for, but in most cases, other hardware is better, and there is nothing wrong with saying so, or moving past the Rπ. I’m lying next to a RK3566 machine right now, sorting out issues with the ARM version of Fedora Workstation, looking at how to build the native WiFi module for it from source, and maybe try debugging an issue in that module’s code that is causing a memory race condition. Although that last one is past my typical pay grade. - So I’m not all fluff here.
That is just my $0.02.
You are better ordering from neither. Amazon group batches their inventory. Their “sellers” appearance is just a price fixing scam. There is no way to trace the stuff Amazon sources to any specific seller. So everything from them is sketchy. The same applies with eBay. Most people are legitimate, but there is no effective way to tell who is or is not legitimate.
There are two ways of looking at this. One, assuming you will install Graphene, the way Graphene uses the Trusted Protection Module TPM chip is to not trust any unregistered code. So a person will not be able to do much to the device to compromise it as far as I am aware. This is conventional type attacks. The second way is more abstract of what is technically possible but improbable and probably never happens in the wild. For instance, one unlikely aspect to be attacked may involve the modem. I am not certain what the Pixel’s actual architecture involves between the SoC and peripherals. Often, the modem on mobile devices is another sophisticated microcontroller. This is capable and entirely independent compute device. The OS is interfacing with some kind of API, but is not privy to what is actually running on this hardware. If it was eavesdropping and communicating over cellular or WiFi, you would not know about it. These devices are undocumented and proprietary hardware too. The orphan kernel scam used to artificially depreciate hardware is based on the proprietary undocumented SoC and modem.