Relay surge protection:
https://forum.digikey.com/t/component-options-for-relay-coil-surge-suppression/7789
Push-pull solenoids:
https://forum.arduino.cc/t/6-v-solenoid/583114/5
https://core-electronics.com.au/guides/solenoid-control-with-arduino/
https://bc-robotics.com/tutorials/controlling-a-solenoid-valve-with-arduino/?srsltid=AfmBOoon9JX5cP5I_5-CW6vQ1tiMdz80n8bOgy78wdohH4E4FA4cS6rb
https://www.instructables.com/Controlling-solenoids-with-arduino/