To me, its a yes and no. If you think that you are a junior practitioner then i would recommend you do it with real stuff...real incense, flowers and candles. Making offerings shouldnt work in our conveniences, we must make an effort to it...its part of the preliminaries for higher practices in future.
But instead, if you are a highly attained practitioner, you might not be necessary making offerings pysically but also it will b as powerful in visualisation due to many years of stable meditative practices.
I would conclude to say theres no right or wrong, but to which method is the best method and effective.
Diablo... I think it would be a very clever and smart idea to have such an app... but I would probably create an app where I can easily get all my prayers just by keying it in and immediately getting it wherever I am.
As for virtual offerings... I suppose it would be okay if ur traveling a lot and on the go that u cannot find time to make offerings on your shrine but then again there are prayers for offering up food which one can do even when traveling... so not really necessary. Just offer what you eat before you eat, 3 meals a day?
As for other offerings, if you have HYT and a trantric practitioner, i heard there is a kind of visualization and prayer am sure where you offer up what you see, smell, hear that is pleasing to yourself. So no need app for that at all. So in fact Buddha is really really amazing and has taught us so many ways to accumulate merits in all possible way!
I guess you could use a virtual shrine as an educational tool to teach people to actually do real offerings, how to do them and the benefits of it all would be really cool.
So having said all that... it is much more personal and nicer to actually go out there, make the effort and be generous and actually buy the offering, hold it in your hands and do your prayers infront of your Buddha and offer... the focus, meditation, action, effort... everything creates an accumulative cause for the result we want.... attainments