I’ve modded by ESP8266-Pro module from RobotDyn, lifted the flash chip’s PIN 3 and 7 and connected them to VCC, previously already flashed in DIO mode using ESP Flash Download tool.
Was able to use GPIO 9 and 10 to blink LEDs no problem, so 9 GPIOs free if I keep UART and I2C
I had some troubles with the inrush current of the 2000uF capacitor charging, was initially using a 2A boost converter module with a small SOT23 MT3608 IC but its built-in soft start wasn’t that great and the 5V USB power adapter goes into over current protection for a couple of secs until it’s charged up.
I then switched to a common XL6009 based QSKJ 4A boost converter and that one seems to far better (also have an ENable pin broken out if I have enough GPIOs to make use of it)
Also, if I don’t disconnect the boost converter’s output after charging up the cap and try to switch on the valve, it will keep sinking lots of current and you see the LEDs dim, had I have the ESP8266 connected for that test, no doubt it will reset.
So either have a separate PSU for the ESP8266 and a beefy 24V PSU just for the valves (of which I do have a spare one) or find some sort of way to limit the in-rush current as well as to disconnect the boost converter, using a MOSFET perhaps?
As for the L298, with its output paralleled, I was able to switch on/off the valve at 24V/2000uF during my test.