rPi 4 are Weak, NOT cheap, Old (2019), and NOT power efficient (compared to a modern low voltage CPU)
I've been testing almost every Node in a box on rPi, and all the bad experiences below did happen to me at least once.
rPi were designed in and sold as cheap toys to learn and experiment on DIY project using GPIO pins.
They need assembly, heatsinks, screwing fans, plugging cables to the right PIN, ect ect.
Come with cheap unpredictable fans that often don't last.
The 5v3A power supply that comes with it most of the time is cheap and breaks.
rPi only takes in 5 volts over that USB-C, some high quality power supply delivers ~4.9v and will trigger under voltage instability and throttling.
Most newer, high quality power supply WILL NOT WORK, as they will try to jump up the voltage to 9, 12 or 20v instead of staying on 5v
5 volts mean that a high quality USB cable of relatively short length is required to make sure there are no voltage drop on that low voltage line.
It's near impossible to find a charger that is above 2 AMP while the rPi needs 3A depending on the attached storage.
Installing the OS on an SD card will lead to more corruption if the power is lost to the rPI
The SD card has low and unpredictable write count. The SD card will become read only after a while.
There is no way to attach HDD storage without a extra active USB to SATA adapter.
This USB adapter is unpredictable and unreliable, might break on you, Might only work at USB 2.0 Speed
No way to install the hard drive in a clean way, Most of the time the drive is left dangling on it's cable or is being taped to the bottom of the the rPi casing.
The USB to SATA interface is slower than direct NVME or SATA connection.
Being digitally sovereign is not ONLY about running a Bitcoin node to verify your transactions.
Doing ANYTHING more than running a Bitcoin Core and a light electrum server (electrs) to verify only a small personal wallet will tax your rPi beyond it's limit.
For about 100$ There are used, field test, computers that are about the same size, made of metal, 10 times more powerful, 2+ times the ram, Have ports for direct attachment of SATA and NVME drive. Wifi, Bluetooth, Have a very reliable power supply. All you might want to do it swap the HDD for a bigger 1 or 2tb one and boot from a USB stick to install a new Linux OS.
The Electricity savings are ridiculously not worth it give the hassle. Each savings of 5 watts is equal to (0.005kwh) * 0.07 * 24 * 365 = $3.00