Fractional REI: Secondary Markets?

[Jeff Lawlor]

Fractional REI companies (Roofstock, Arrived, etc) have caught my attention. What happens if I want to sell my shares? I'm concerned this is like trying to unload a timeshare where you get pennies on the dollar.

Arrived talked about a starting a secondary market for buying/selling shares. Are companies where they have a secondary market up and running? I'd love to see some secondary market pricing vs. buying directly from the company offering the shares.