A friend of mine wants to create "tokens" signifying the completion of certain corporate milestones, e.g., the acquisition of X customers,

This is possible, Bitcoin (and some other cryptocurrencies) allow users to create 'non-fungible tokens', which can be individually tracked through the blockchain history.

and then "monetize" these "crypto" tokens as "asset backed securities."

An 'asset backed security' generally refers to:

a financial security collateralized by a pool of assets such as loans, leases, credit card debt, royalties or receivables.

So I'm not sure how a 'corporate milestone token' would satisfy this definition. If there were some monetary reward available for redeeming said tokens, perhaps that could loosely fit, but in that case this seems like a very contrived system to build. Why not just issue the reward directly to the recipient in the first place? If you have to trust the corporation to pay out your reward, why not just trust them to keep a version-controlled excel spreadsheet with all of the data stored in it? That would be a much cheaper and easier system to implement.