You can choose to see OI as asset-denominated (e.g. 1000 BTC), USD-denominated, or both.
How I usually interpret OI: Price up, OI up = longs opened = bullish Price up, OI down = shorts closed = bullish on HTF, or counter-trade on LTF Price down, OI up = shorted opened = bearish Price down, OI down = longs closed = bearish on HTF, or counter-trade on LTF
I find the indicator useful on 1-minute charts to identify liquidations and compare perp v.s. spot patterns.