Vjylku

I don't know if there are any special instructions to follow, or if the Ubuntu (Ubiquity?) installer automatically detects this (and if it does detect the additional internal drive, what exactly would it do in the background)? I am not trying to dual-boot (I just plan to use a Windows 10 Virtual Machine, but for that, I'll need more disk space: I was planning to purchase a computer with a small 128GB SSD and a 1TB HDD, but I didn't know if Ubuntu would automatically install the bootloader and essential?? things on the SSD, and then I could use the HDD for other storage. This is because I had heard that SSDs are faster for starting up the operating system and for everyday use, but HDDs are still better for long-term storage. Is this correct as well?)

but I didn't know if Ubuntu would automatically install the bootloader and essential?? things on the SSD

The UEFI part you start from BIOS. It will offer to install the bootloader on the FIRST disk it sees (sda) and offer you the option to pick another disk (sdb).

I don't know if there are any special instructions to follow,

Nope.

or if the Ubuntu (Ubiquity?) installer automatically detects this

Yes.

Basically:

• Set the ssd up with a mount called /
  



• Set the hdd up with a user named mount (I use /dicworld)




• What I tend to do next is edit ~/config/users-dirs.dirs to point the directories in home to /discworld. The personal files are best kept on the hdd. The config in /home/ is better kept on the ssd.

This is because I had heard that SSDs are faster for starting up the operating system

Yes. Not just starting up but also starting applications (if the config files are on the ssd)

and for everyday use, but HDDs are still better for long-term storage. Is this correct as well?)

Yes. For video, music and general personal files the hdd is best used as the "fileserver". It is also better to set all downloads in things like torrent programs, browsers to the hdd.

Is there an official tutorial for installing Ubuntu 18.04+ on a device with an SSD and an additional internal hard drive?

Nope. Not "official" since it basically has a high personal influence: what I consider best someone else might believe it not to be. But I did found a AU answer that might be helpful in explaining how to use the "something else":

How to use manual partitioning during installation? See part 2 in this answer: https://askubuntu.com/a/521195/15811

I have Ubuntu 18.04 installed on a 128Gb SSD with no problems whatsoever.

Much depends on what you want to use the machine for but in the majority of cases 128Gb should be more than sufficient and any extraneous files such as videos and photos etc can be directed to the other HD as required.

It is possible to change things round so that you move your ~/home folder to the HD and any content currently in ~/home on the SSD there also.

This is described in detail in this article.

Read down from from Migrating the Home Folder in the article.