If operating under Part.NCO, you do get quite some modern guidance from EASA.
AMC-GM-Part.NCO 135 GENERAL (b):
The documents, manuals and information may be available in a form other than on printed paper. An electronic storage medium is acceptable if accessibility, usability and reliability can be assured. So, we do have a clear statement from EASA towards use of electronic charts, kind of ... We have to see what the local doubleAs will do from the "reliability" sentence (we lately had the discussion on flying high beyond vendor tech specs with an iPad).
EASA pushes electronic even further by AMC1-NCO.GEN.135(a)(10) CURRENT AND SUITABLE AERONAUTICAL CHARTS (c)
The aeronautical data should be appropriate for the current aeronautical information regulation and control (AIRAC) cycle. How can you do that with a paper chart? We have to see, what they make of it too.
If I am right on my knowledge about EU regulations and directives, the application of Part.NCO was in place with August 25th 2016 and does indeed overrule national law. I know, with Kafkaesque-EU that may not mean anything, certain EU districts love to frequently break EU laws and others were totally surprised by a treaty which was worked on for 20 years (and their clerks were neither commanded to learn nor interested in following their work environment ...). Again, we see what will come out of that.
One last word on "EASA approved" software, there is none as there is no "approval" or "certification" procedure. The only difference of Jeppesen MFDVFR is the missing disclaimer at program start and if this is worth anything, we will be able to estimate once it will be taken in a case to court.