I bought a little computer a little smaller than two packs of playing cards. That's where the node and all personal server stuff runs. It's so compact and badass. Don't know why anyone who cares enough to run a node would bother with a Pi.
I think for me the attraction of the Pi was the large ecosystem surrounding it, meaning it has a lot of third party cases, etc, allowing you to customize your setup. For example, my node has a customizable compact display that was also built as a casing for the Pi.
Not to mention, a lot of people myself included got into node running thanks to raspibolt.org
Probably it is suboptimal to use the Pi in terms of cost and technical specs, but it was my first node built and I still love it
Real-time clock (RTC), powered from external battery
Nice! Bitcoin needs an accurate source of time to work properly, as blocks can be invalid if they're too far into the future. So having an RTC helps avoid depending totally on trusted time sources.
I've tried to run a Bitcoin node on Pi 4, but its SD card gave me errors due to (?)overheating so I've switched to a Rock 5B. It has 16GB RAM, a 1TB SD card works perfectly and it also has an M.2 slot (so I can replace the SD card with an NVME SSD drive). It's not an advertisement, just my own experience.
It looks like RAM is fixed at 4 or 8 gb options. My understanding is that since the UTXO set is at around 8gb already nodes should have 16gb memory to perform decently. Therefore, this looks to me DOA in terms of using as a Bitcoin full node. Even if it had a 16gb option, why would anyone pick this over a used Thinkpad or else an Odroid or an Intel NUC or something like that? It looks like it's going to use more power too and recommends active cooling. One of the advantages of the pi 4B was low power draw and passive cooling so really not seeing much point in this. I think the reality is that the Bitcoin Blockchain has grown beyond a low power ARM SBC, anyway.
There's no need to keep the whole UTXO set in memory. Most of it is rarely read from disk during normal operation. The dbcache (i.e. UTXO set cache) is 450MB by default and you usually only want to increase that for IBD performance.
I guess low consumption is still the reason why to use these devices. Orange Pi 5 plus with 16gb of ram would still be my preferred option today, but it is a bit expensive.
Pi nodes are pointless already. For personal use (i.e. full node for cold storage and occasional on chain spending) they introduce more complexity and security risks than simply buying an old laptop, replacing the SSD and running Bitcoin Core with Sparrow.
For "professional" use (i.e. running a lightning node) then mini PC or server hardware is far more appropriate.
dbcache(i.e. UTXO set cache) is 450MB by default and you usually only want to increase that for IBD performance.