Internal oscillator means you can get the core running without an external crystal for basic bring-up, though the Ethernet PHY clock will want a precision source.
Built-in data converters
Two 12-bit DACs and sixteen 12-bit ADC channels are on-chip. That answers the question: yes, the STM32F746VGT7 has a built-in DAC — two of them, in fact. For a control loop that needs analog output alongside sensor readback, you can skip the external DAC and save board space.
ST lists the STM32F746VGT7 as Active.