Anybody here have experience using Vanguard Brokerage Services to buy T-Bills I have used Vanguard to buy and sell Indiv stocks, ETFs and mutual funds for 30 plus years but haven't seen any option anywhere to purchase a T-bill.

Maybe it trades like a stock, I place a market order for 100 shares of 52 week Treasury Bills and that order fills at the next auction for a cost of the $100,000 face less the discount rate representing the current auction's interest rate. All that would be fine provided the 52 week T-Bill has a symbol that I can buy 100 of. But I can't seem to find that "symbol" so there must be some other mechanism.

I understand I could open a Treasury Direct Account and that would fine for my taxable investments. But I also would like to buy within my Roth. Reading on Treasury Direct web site, I didn't see an option for them to be a Roth Custodian. I looked on Vanguards website at it implies it can be done but doesn't explain how. Hence my question to board. TIA for any info.