i believe they have very limited if any access to private keys and only interact with keys on a scheduled and limited basis as all is stored coinbase custody so perhaps a "random" proof of reserves is out of the question however if they coul incorporate it into their quarterly filings it would be awesome.

Also of note Vanguard recently "prevented" buying of GBTC as it is a digital asset over the counter security that they no longer support. I imagine many people have an issue buying it in their retirement accounts which doesn't help the gap on NAV from closing. Fidelity has also blocked my from adding it into an IRA that is company sponsored.