Happy to try and help – full disclosure: I have an emr company, www.atlas.md
Ultimately an emr is a tool and you should find the tool that fits your needs/budget best.
Yes you could have charts in google (preferably the google business suite for security): google docs which are like word files, google spreadsheets = excel. And have a file for each patient etc.
If you sell a practice, they may or may not want your charts so its usually something that is negotiated on a per clinic purchase basis. If they buy the charts, then they'll be the custodian of records – so you'd be incentivized to make a purchase of your practice dependent on them taking the records.
Or if you like to keep your records, your state board of medicine can tell you how long you're legally required to hold on to those records. Yes, you can keep them digitally but I'd recommend several back ups: google drive, dropbox, and a few thumbdrives, maybe 1 at home and 1 in a safety deposit box at the bank...seems unnecessary, but so much easier than a patient that wants to make a fuss b/c they can.
Feel free to call/email if youd like to chat further.