Werner

https://docs.armbian.com/Process_Contribute/#adding-a-new-board

I don't think there are pre-built images with both ha and de by default. 
You can try to build your own by adding this extensions to your own userpatches and enable it: https://github.com/armbian/os/blob/main/userpatches/extensions/ha.sh
 
 

https://docs.armbian.com/User-Guide_Autoconfig/

This should have been addressed: https://github.com/armbian/linux-rockchip/pull/373
May take a while until an updated kernel is available via apt. You can always build a up-to-date package by yourself using the build framework.

Raspberry images are compatible from 3b up to 5b

Here are some:https://github.com/armbian/community/releases/

Maybe this helps? https://forum.armbian.com/topic/29427-shrink-backup-a-tool-for-backing-up-sbcs/

direct boot from nvme isn't possible. Boot loader (u-boot to say) must be present on SPI, eMMC or microSD.

Check here https://github.com/armbian/community/releases/tag/25.5.0-trunk.256
or on a mirror with archive https://docs.armbian.com/Mirrors/#current-mirrors
for what you are looking for. We're aware that some links are broken for yet to be determined reason.

There are for once some inconsistencies in terms of prefixes across various soc families and for the other configng isn't perfect (yet ).
Feel free to share your issue at its repository: https://github.com/armbian/configng/

fixed

Not sure if it is possible to use a local kernel source directory. At least I don't know how to do that. Easiest is probably just to create a repo and define url and branch in board your custom board config.

Yes, DB9 won't work.
But if, as eselarm mentions, a proper chip is on board already a simple usb-a to usb-c or c-to-c cable should do.
Check dmesg when connection to see what pops up.

Between days and month. Depending on time, issues, regressions,... 
Refrain from asking for ETA. Putting pressure on developers who give you something for free is abusive.

BOARD=uefi-x86

Install code { font-family: Consolas,"courier new"; color: crimson; background-color: rgba(0, 0, 0, 0.2); padding: 2px; font-size: 105%; } qemu-user-static package and retry

Try setting ZRAM_PERCENTAGE=50 where 50 would be half of available memory. Not sure if the builder picks this up.
If it doesn't I'd go the customize-image.sh route and use this to modify the /etc/default/armbian-zram-config file just before assembly closure.

No worries. Everyone here started small
edge and vendor are Armbian terms for kernel branches just like current.
You guessed correct, edge is bleeding edge and usually follows latest mainline kernel (6.14.y today).
vendor is based on Rockchip BSP kernel which is 6.1.y at the moment. While a bit out of date most hw functions work here.
current usually follows latest available LTS mainline kernel.
 
As you're a beginner and most likely just want things to work I suggest to try a vendor kernel based image first.

If a kernel package exists as artifact in oci cache it will be downloaded and used. Only if there is no artifact it will be built from scratch. After a new kernel version is released it may take a few days until oci catches up.
However once locally built it will also be cached locally so it will be re-used if you start another build.

I don't think so. You can check in /boot/armbianEnv.txt if there is panthor overlay enabled. If so, disable it so you can use the proprietary mali blobs.

unsupported host os for build environment. Grant the user access to Docker or use a Noble host.

Use edge or vendor for more features. current will stick to 6.12 LTS kernel which will receive fixes only.

A few days ago jammy and bullseye were moved to eol.
While upstream may support these userspaces a few more years, Armbian does not have the resources to support more than the most current stable releases of Debian and Ubuntu, which are Bookworm and Noble at this time.
 
You can still select them to build when passing EXPERT=yes switch to ./compile.sh but do not ask for support if something breaks. You are on your own.

Great.
Just to avoid cross-contamination. You are sure you have the Orange Pi 3 and not the Orange Pi 3 LTS model?
 
Background: OrangePi naming scheme is kind a ridiculous, makes no sense often enough and introduces confusion. In this particular case they switch to a different PHY chip which I think was migitated by Armbian but not sure if they still have separate images.
 
Seems like a similar topic already exists: https://forum.armbian.com/topic/34024-cannot-attach-to-phy-after-upgrade-to-202381/

That's normal services usually need a few hours to catch up with stuff once a new tag is released. Try tomorrow.
 

Deprecated. Check docs again.