>is wallet-garden a play on words having to do with financial schemes and open source?
No it means a ->approximation<- of what Google and Apple is doing -> Snapstore/Appstore
What was being asked is whether you're aware that the correct term is "walled garden" (and saying "wallet-garden" as a play on words), or if "wallet-garden" is a mondegreen[1] for you (also recently referred to as a "bone apple tea" thanks to the popularity of a certain subreddit[2]).