Joe Offer wrote: Is there an app that I can use that will make it easy for me to transcribe notation to ABC?

I use David Zemsky's Sheet Music Scanner and Reader on my Android tablet - there's an iPad version too. It cost a few pounds when I bought it.

I can photograph the dots and it will play it. It doesn't export to ABC but it exports to MusicXML and there are several apps and programs which will import MusicXML and give you ABC, including Michael Eskin's webtools and EasyABC.

Another app, Playscore 2, is better at interpreting scores but is much more expensive than my Android Music Scanner, and you need a subscription to the 'pro' version to export MusicXML.

Once you have ABC it's just text. All the issues with files and operating systems is irrelevant: people can copy and paste it. And if you put ABC in a post you can also provide a link to play it immediately, as I did earlier with Paul Rosen's ABCjs Quick Editor. That link may fail in future, but the ABC will remain.