Is it currently possible to jailbreak it? If not, have there been Kindle e-readers before without jailbreak possibility, and has Amazon released the jailbreak possibility later?
My motivation for jailbreak is to display the cover of my book on standby, and to install reader software that shows the number of "pages" left in my book or chapter (the number of times I can press next page before the end with current display settings).
Is it currently possible to jailbreak it?
Only if the original firmware (5.9.0.5.1 or 5.9.0.6.) of your Oasis 2 hasn't been updated. For more information see this website.
If not, have there been Kindle e-readers before without jailbreak possibility, and has Amazon released the jailbreak possibility later?
Amazon has never released any jailbreaks. Hackers have reverse-engineered the firmware and developed jailbreaks for specific firmware versions.
