You can try this "dirty" trick to figure out what the data corresponds to type of wallet.
Get Python, john the ripper and hashcat.
put your text in a file called wallet.json
With the run tools in JTR try the following on the strings:
python bitcoin2john.py wallet.json > bitcoinhash.txt
python blockchain2john.py wallet.json > blockchainhash....
There are a bunch of +'s and /'s.
That strongly suggests it is data in Base64 encoding. Note that, in this case encoding does not mean encryption, just a specific printable representation of binary data.
Does anyone have any idea what I could try to see if this is it?
It seems several different wallets might use Base64 encoding, including: