I'd LOVE to write more about my homelab, but it's a work in progress that continues to evolve, and I haven't documented things as well as I'd like to!
There's not really much more to it than that.
You may need to learn a ton as you go if you don't know the basics of the area the project is in. Software based projects are probably easier than hardware based projects in the sense that you won't lose money to change your mind.
On a RPi, you can always just rewrite the SD card and carry on. No harm, no foul. You're not counting on it like you would your main machine (until you are).
What are you using for storage? Powered HDD over USB or something?
I use a combination of official RPi 4 power supplies and an Anker 6-port USB power block that I'm pretty sure tops out at less than 3 amps.
More importantly, everything is plugged into APC UPSes.
However some USB SATA IC's have issued with it on Raspnberry Pi[2], requiring one to disable UASP. I have some JMicron-based USB-SATA adapters which falls into this category.
[1]: https://www.jeffgeerling.com/blog/2020/uasp-makes-raspberry-...
FWIW, I did see this but it's $$ : https://store.uputronics.com/index.php?route=product/product...
The DNS servers, less so: CoreDNS is reading my internal DNS zone from an Amazon Route53 private zone. This was my way of dealing with running two DNS servers concurrently, but it wouldn't do well in a WAN outage.
And, once I lose internal DNS, I lose everything else too
I've written about the CA for Smallstep: https://smallstep.com/blog/build-a-tiny-ca-with-raspberry-pi...
I wrote a piece about the NTP server, but I haven't had a chance to post it yet. There are some good resources out there for creating a local NTP server, though. It takes some time and effort to get everything dialed in, because GPS and NTP are both finicky and easy to misconfigure.
I'd LOVE to write more about my homelab, but it's a work in progress that continues to evolve, and I haven't documented things as well as I'd like to!