You can find resources for each categories but don’t think there is one that would cover everything and the reason is there is always several ways to do things and not one way for all.

First you need to choose an OS. You have a few choices here, a good way to start if you don’t have much knowledge on linux command, docker… is to use something like Casa OS, Zima OS which are much more beginner friendly, it basically has a store where you can pick what you need to selfhost. If you already feel more confident and want absolute full control you can use proxmox instead.

Once you settled your OS, you need to pick what to use sleefhost image, music… Here you have again several solutions, you can check immich for pictures, jellyfin for music/video, home assistant for smart home.

A pi5 with 1gb ram will always be cheaper but that’s not enough ram for your usecase, search n150 at Aliexpress, you can often find some mini pc for around 150-160€ on sale with n150, 12gb lpddr5 (or 16gb ddr4 sodim) and 500gb SSD. https://a.aliexpress.com/_EQ5k2Uu This one was 153€ couple of days ago. Thay are other Chinese brand like soyo, beelink, bmax that have similar hardware. They are not as good as NUC, but they do the job for way cheaper.

Home assistant is a beast, not sure openhab can actually match it today. Unless you already have a pi5 and a SSD (avoid micro sd card), you could consider a mini pc with n150 (or n100) processor. It doesn’t consume much power (close to pi5) and it will be more powerful and more Ram which will be useful for immich.

Start with zigbee first, much more mature than thread. I don’t personaly use thread but i believe some zigbee dongle also can deal with thread at the same time.

About the setup. If mini pc, you can use proxmox so you will be able to create a VM for home assistant and another one for immich.

That might depends on how your AC is working, I recently did the same at my dad’s house and run into issues because the temp control for the unit is reading from the remote. So when I sent infrared command to turn off unit, it worked as expected for some minutes then turned back on because remote sent back command as temp wasn’t meet. Still need to do a lot of testing to find a way to make it work, might need to disable remote and use some temp sensors for the triggering part but not sure how that will work, might need to use some hysterisis friendly climate addon for that…

Can’t answer sorry

Comparison of self hosted photo library https://github.com/meichthys/foss_photo_libraries

I can’t remember any name but search for f2f (friend to friend) p2p. Basically a private way to share files over p2p to limited people you have accepted without any use of tracker like P2P use

+1 those are really great. And should be just below 150

I am mainly reading on iPad due to screen ratio, I’m self hosting yacreader library and use yacreader app (server is free, app is one time payment on iPad, does have an android/windows client but not developed as iOS version). If I remember correctly, I think there is also Panel on ipad that do the same (would need to check). On android, I need to check and can answer tomorrow (almost 1am here), could be cdisplayex but unsure.

i don’t know any on computer but some app offer that on android/ios. i guess they look for some kind of contrast pattern to determine each frame.

Did try and it does work really well on some but not all garphics novel / comics

Does it have access to boot menu? If so, change boot order so it goes to usb first. You will then only need to create a bootable usb stick with Linux on it

I’m using home assistant, with mqtt which acts for many things and I get notification in different way depending the needs. Could be home assistant app or telegram or lighting up some light or sending voice messages to a speaker. All notifications are triggered by automations looking at states. Haven’t done it but automation could be re launched automatically until (for exemple) I press a button or responding to telegram message