Ghost is open source. You can selfhost. It’s just that aggressively advertising their (paid) hosting services on the official website

Which is why the comment you where replying to specified

in civilised countries

The implication beeping that the US is not. Because in a lot of other countries surprise clauses in your T&C’s is illegal

If you don’t want to do that, then you can buy a bootable drive (for example here: https://www.shoplinuxonline.com/mint21-usb.html)

Using a different tool to create a bootable drive is just a part of installing any operating system, not just Linux. If you ever need to install windows on a pc that doesn’t have it installed you will see the same process.