I wish articles like this would include recommendations on how to choose hardware to run your self-hosted services on.
It all comes down to what you want to spend vs what you want to host and how you want to host it.
You could build a raspberry pi docker swarm cluster and get very far. Heck, a single Pi 5 with 4gb of memory will get you on your way. Or you could use an old computer and get just as far. Or you could use a full blown rack mount server with a real IPMI. Or you could use a VPS and accomplish the same thing in the cloud.
No, you couldn't, and no, you wouldn't.
To build a swarm you need a lot of fiddling and tooling. Where are you keeping them? How are they all connected? What's the clustering software? How is this any better than an old PC with a few SSDs?
Raspberry Pi with any amount of RAM is an exercise in frustration: it's abysmally slow for any kind of work or experimentation.
Really, the only useful advice is to use an old PC or use a VPS or a dedicated server somewhere.
Then I had my old PC and it was very good but I wanted more nvme disks and motherboard supported only 7.
Now I am migrating to threadripper which is a bit overkill but I will have ability to run 1 or two GPUs along with 23 nvme disks for example.
Intel n100 with 32GB RAM and single big SSD here (but with daily backups).
Eats roughly 10 Watts and does the job.
I did use my old PC and it was working very nice with 4 sata ssds, in raid 10.
And as I already said on other comment - in my case power does not matter much. Space too.
There are other cards like that i.e. https://global.icydock.com/product_323.html This one have better support for smaller in size disks, much easier to swap disk but costs like 4 times more.
I think it could put even more drives in my new case I.e. using pcie to u2 card and the using 8 drives bays. But this would cost me probably like 3 times more just for the bay with connectors. and I do not need that much space.
https://global.icydock.com/product_363.html
If you like u2 drives then icydock provides solution for them too. Or if you want go cheaper there are other cards with slim-sas or mcio https://www.microsatacables.com/4-port-pcie-3-0-x16-to-u-2-s...
But u2 disks are at least 2 times more costly per GB. Like 40tb costs 10k$. This is too much IMO.
For every clown like me with massive RAM in their colo'd box, there is someone doing better and more amazing things with an ESP32 and a few molecules of RAM :D