A Rule 10b5-1 plan solves a problem you do not have: insider-trading liability while holding material non-public information about a liquid public stock. You have no public market and no such constraint, so the instrument is irrelevant.

What survives translation is the discipline underneath it: pre-committing to the terms of a sale before you know what the price will be. The private-company form of that is a shareholder agreement with a pre-agreed valuation formula and buy-sell mechanics, negotiated while everyone still likes each other. If you have co-founders or will take outside money, that document is the thing Kim’s filings should remind you to go read.