US T-bills

At the moment there are 1-3yr short-term ETFs but not any with less than a year maturity. Which are great low volatility investment options. Would you consider adding 0-1yr US Treasury bonds (or UK Gilts) like one of the following?

  • Vanguard U.S. Treasury 0-1 Year Bond UCITS ETF(Acc)
  • iShares $ Treasury Bond 0-1yr UCITS ETF(Acc)