The ALC897 is fully supported by the snd-hda-intel kernel module (Linux kernel 5.4+). Users do not need proprietary drivers. However:
Yes. Absolutely.
Unless you are using $300+ studio headphones (e.g., Sennheiser HD 600s), you will not notice the difference between the ALC897 and a high-end sound card. Realtek Alc897 Driver
For competitive gaming (Footsteps): The ALC897 is fine. The positional audio depends more on the game's software engine (Dolby Atmos for Headphones or DTS:X) than the codec. The ALC897 is fully supported by the snd-hda-intel
The catch: The amplification (power) is weak. If you have high-impedance headphones (over 80 ohms), the ALC897 will sound quiet. You will need an external USB DAC/Amp. Sennheiser HD 600s)
To avoid conflicts: