I used to run a 5 node Ceph cluster on a bunch of ODROID-HC2's [0]. Was a royal pain to get installed (armhf processor). But once it was running it worked great. Just slow with the single 1Gb NIC.
Same here, but on PI 4b's. 6 node cluster with a 2tb hdd and 512 Tb ssd per node. CEPH made a huge impression on me, as in I didn't recognize how extensive the package was. I went up to 122mb/s and thought it's too little for my hack-NAS replacement :)
The functionality: mixing various pool types on the same set of SSD's, different redundancy types (erasure coded, replicated) was very impressive. Now I can't help but look down at a RAID NAS in comparision. Still, some extra packages like the NFS exporter were not ready for the arm architecture
Was just a learning experience at the time.
[0] https://www.hardkernel.com/shop/odroid-hc2-home-cloud-two/