I used to run HA on an RPi, but eventually migrated it to a similar NUC. The RPi eventually just wasn't powerful enough (peak compute needs), while the NUCs are still quite cheap. And you can run a surprising amount of Proxmox VMs and LXCs on barely a few cores and gigabytes of RAM.
I use an RPi 4 w/ 4GB of RAM and a 1TB usb 3.2 SSD and it flies through all my workloads. Though I don’t do any video encoding things.
Thanks for sharing, your comment helped me track down that my RPI HA was disk constrained. I didn't think to add a USB.
The cool thing is that it's very easy to migrate it to better hardware. HA backup and restore system is highly reliable. For this reason I can definitely recommend an RPi to start with, and who knows perhaps it will be enough forever, but if not then moving is a matter of ~one evening.
Wow, not sure how to interpret your experience that a RPi wasn't powerful enough to manage watering a few plants. I can only suspect the overall software setup is massively bloated.
If you want to run EspHome inside HA, and you recompile the devices (every release of EH), you want a decent processor/disk. The ESP stuff is a surprisingly heavy compile for a puny microcontroller.
A recent RPi is sufficient to handle a few plants - though, yes, recompilation will take time. The ESP is a beautiful piece of software, hence I highly recommend it. My native language has an expression that describes this situation perfectly: the appetite grows with eating. Next thing you know you have 2k or more entities, and your HA even handles some video feeds.
The important thing is that it's pretty much always easy to make an upgrade thanks to the good design of the backup system. Don't forget to set up backups in either case, it's a sin to not use such a complete system :)