it just depends on how much resources the app needs. some need more CPU cores, RAM, or storage than others.
the main selling point with PikaPods is having them manage app installs and the server for you, so youre paying a bit more for that convenience but there are other options that would work out cheaper if you dont mind doing a bit more of the work yourself.
the Zimaboard for example, is a small and cheap SBC similar to something like a Raspberry Pi that has ports to attach an SSD or HDD drive. it comes preinstalled with CasaOS which is a simplified Linux OS that makes it easy to set up drives and it has a similar 1-click install app store to PikaPods.
theres other options like renting servers online from the likes of Hetzner or Netcup and then installing CasaOS yourself, or there are other things that manage app installs like YunoHost or Cloudron. theres almost too many options in a way!
i started out years ago with Synology NAS, which was very expensive up front but also very easy to set up and they have a good selection of web apps that they make themselves with mobile apps that are decent enough. i used that for years and then just gradually learned more about self-hosting over the years, so thats not a bad route to take either if youre interested.
just a FYI, Synology is based in Taiwan, and the Zimaboard company is based in Hong Kong/China. i havnt done much research into EU alternatives yet
good answers already so i will give you a different example.
my basic understanding of it is that docker was created originally for developers. im not sure if anyone planned for it to be a way to package up software for end users.
before docker existed you would have this issue where devs would be working on an app, say jellyfin, but each dev might be on a different platform (windows, mac, linux), or be using a different OS version, or different versions of whatever software... which meant it happened often that the app would work for one dev but not another. maybe one dev updated C# to version 2.3 and told everyone else to update, but someone missed the memo and is still running version 2.2 and now jellyfin wont work for them and time would be wasted trying to figure out where the mismatch was
so docker was a way to fix that "version hell" problem. every single thing that is needed for the app to run is kept inside the container. one dev will update something to a new version, then that container is shared to all other devs and each dev only has to worry about updating to the newest container before they start working on something.
app settings are kept in a separate location and the app data in another. in the case of jellyfin, the app data would be the movies or tv shows folder for example. then when you start the docker container, it will symlink those 2 locations/folders inside the container and the jellyfin app can access them as if they were folders that were actually stored inside the container.
so having the settings and data separate like that makes it very easy to update the container to a new version, or for a developer is probably useful being able to rollback to an older container for testing. its similar to how say windows puts the program files in one location and settings in the appdata folder
for end users its handy if theres a new version of jellyfin or whatever that isnt released yet but you want try it out, you can run 2 containers at the same time and both of them can access the same settings and data. (maybe with the newer one in read-only mode so it doesnt mess up your settings or data!)