espflash: ESP32-PICO-D4 - Error: flash chip not supported

I have an ESP32-PICO-D4 with 4MB of flash, I believe something like (but potentially not exactly) this: https://www.aliexpress.com/item/4000473398801.html

I’m following along the xtensa-rust-quickstart, and rying to use cargo-espflash from Crates.io got me some unexpected errors:

$ cargo espflash --chip esp32 --example esp32 --target xtensa-esp32-none-elf --speed 460800 --features="xtensa-lx-rt/lx6,xtensa-lx/lx6" /dev/ttyUSB0
thread 'main' panicked at 'Unable to parse command-line arguments: unused arguments left: --target, --speed, --features=xtensa-lx-rt/lx6,xtensa-lx/lx6', /home/toby/.cargo/registry/src/github.com-1ecc6299db9ec823/cargo-espflash-0.1.1/src/main.rs:13:29
stack backtrace:
   0: rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::result::unwrap_failed
   3: cargo_espflash::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Installing from this repo directly (via cargo install --git https://github.com/esp-rs/espflash/ cargo-espflash) seems to have gone better, but I get “flash chip not supported”:

cargo espflash --chip esp32 --example esp32 --speed 460800 --features="xtensa-lx-rt/lx6,xtensa-lx/lx6,esp32-hal" /dev/ttyUSB0
   Compiling xtensa-quickstart v0.1.0 (/home/toby/git/esp32/xtensa-rust-quickstart)
    Finished dev [unoptimized + debuginfo] target(s) in 0.66s
Error: flash chip not supported

Is this a limitation of the library currently, or potentially a bug? Whatever the solution, this may ultimately fix https://github.com/MabezDev/xtensa-rust-quickstart/issues/30