From the ESP-WROOM-02U datasheet, here are the pin groups you asked for.

The datasheet explicitly identifies these boot-related pins:

For normal flash boot, the extracted boot notes indicate the expected strap state is GPIO15 low, GPIO0 high, GPIO2 high or floating. For serial download mode, GPIO0 is held low during reset while GPIO15 stays low and GPIO2 stays high/floating.

On the module pin list, the clearly input-only exposed pin is:

I do not see any other module pins explicitly described in the datasheet as input-only in the exposed 18-pin module pin table.

For the module pins, there are no dedicated internal flash pins exposed in the 18-pin connector list. The datasheet says the module integrates 2 MB SPI flash, and the internal schematic shows the flash connected to the ESP8266EX with internal signals such as SD_DATA_0..3, SD_CMD, and SD_CLK, which are shown in the internal schematic rather than as exported module pins.

So the practical list is:

If you want the closest related external SPI-capable pins, the datasheet lists HSPI on:

But those are interface pins, not the module's internal flash bus pins.

There are no USB pins present. The datasheet-extracted pin list and interface table include UART, HSPI, I2C, I2S, IR, PWM, ADC, etc., but no USB interface or USB pins are listed.

If you want, I can turn this into a pin classification table for the whole part project, so you can tag each terminal with Bootstrap, Input, Communication, Power, Ground, etc.