At one point I think there was a website which when provided with an mkv file allow you to watch the movie and make the decisions. Not sure if it is still around or what it was called

Another once in a lifetime recession

It is unlikely that the service itself will delete your data. Although if it is one of those job board sites like indeed that try to build a profile and sell it to employers it might make sense to delete your account so your information is no longer forwarded

This is the community fork that is still maintained. There are multiple instances like invidious and from what I understand it is relatively easy to self host. Since it is only for short term file storage and its E2EE I do not really mind using one of the public instances.

It just appeared in my recommended again so I suspect you are correct

Savings in battery. It’s mostly just from not running google play in the background. If you then go on to root that custom ROM you might be able to use some specific root tweaks. I suspect the savings for a custom ROM to be 10% or less. Airplane mode and battery saver will help a decent amount which is available on stock.

I might consider kodi since it will probably be more organized. Vlc will have normal file navigation but with kodi it will organize everything into movies and TV shows. If its going to be a purely offline device then you can just flash a custom ROM and see a decent amount of savings. It will likely be difficult to find a current generation phone with an sdcard and a tablet might make more sense for this use case. If you know you are gonna flash the device you are going to get you should make sure it has decent custom ROM support. Generally if it has an official lineageos build then it is well supported. All of this might honestly be more trouble than it is worth if you are not experienced with flashing a custom ROM so maybe just start with stock and see if you actually need to first.

Also if you do go this route and are concerned about privacy and security you can get a cheap vps then setup a VPN (wireguard probably) on the vps and have your home server connect to that. Then you can forward the vps ports to the VPN IP of your home server. This means that you don’t need to have port forwarding or even a dedicated IP at home and users don’t get your home IP. Keep in mind you need a vps that is relatively close to your house to keep the latency down as this setup will add twice the latency between home and the vps to the connection.

Just an FYI getting a vps or dedicated server that is fast enough for Minecraft modpacks is going to be fairly expensive. It might be cheaper to get shared hosting for the MC server and a separate vps for the docker stuff.