My experience with these is terrible. I install a JetBrains IDE via a package. I spent a very long time trying to debug a CMake problem that I assumed was my inexperience with CMake. After attacking various processes with strace, it dawned on me that the problems were caused by the IDE not being able to see files in /usr/local. A sandboxed dev environment! Lost for words... A relatively inexperienced dev would have a terrible time with such a thing - it couldn't even see dev headers & libs installed with apt.
This is the biggest problem with these containers at the moment, you don't get any feedback what permissions are missing, first you need to understand this is a permission problem with the container itself and then to understand what permissions are missing and then apply them correctly.
For flatpak there is an api you can use to change permissions but for snap what I can remember that is not something you, the user, can change, that is up to the maintainer to enable them.
Applications like an IDE uses a lot of different resources so I gave up on using that as a flatpak, luckily Jetbrains ships their IDEs as tar.gz binary package you can use instead.
Flatpak works best when the application is very self contained, like Spotify, it streams music from an internet service, it doesn't require any special permissions.
I used Bitwarden as a flatpak, it had limited file access with one granted directory (Downloads), I was going to download an attachment from the Bitwarden application, the file saving dialog started one directory up from Downloads, you had to pick and open the Downloads directory first before saving, however I managed to save my attachment in that starting location outside of Downloads, some void directory that I never found.
One time I didn’t paid attention, installed Snap package instead of the native binaries, and then I spent several hours debugging “access denied” status returned by mq_open https://man7.org/linux/man-pages/man3/mq_open.3.html kernel API in my program which only happened when called from a C# program, but not C++ program running under the same user account.
The (unofficial) JetBrains flatpaks have never worked for me for that reason, I don't know why flatpak keeps them around. I recommend JetBrains Toolbox[0] for managing their IDEs.
You discovered the one area that doesn't work well yet. Dev tools don't work great because they typically need access to just about everything. They either ask for very broad permissions or the app has to add support for portals - of which there may not be some that they need yet.
Can't upvote this enough. As other commenters have pointed out, understanding why certain features/patterns don't work in a given app due to sandboxing is a major hurdle.
Yea, a while back I tried out a flatpak for filezilla, but because it was sandboxed I couldn't set the default editor to anything on my actual machine, so uninstalled that and went with a deb which worked just fine
