Cargo Features

[dependencies]
bitcoin-waila = { version = "0.3.0", default-features = false, features = ["no-std", "std", "rgb"] }
default = std

The std feature is set by default whenever bitcoin-waila is added without default-features = false somewhere in the dependency tree.

no-std

Enables alloc of nostr ^0.26.0, no-std of bitcoin ^0.30.2, lightning ^0.0.119, and lightning-invoice ^0.27.0

std default

Enables std of bitcoin ^0.30.2, lightning ^0.0.119, lightning-invoice ^0.27.0, and nostr ^0.26.0

bitcoin:

At least one of std, no-std must be enabled.

The no-std feature doesn't disable std - you need to turn off the std feature for that by disabling default.
Instead no-std enables additional features required for this crate to be usable without std.
As a result, both can be enabled without conflict.

rgb = rgb-std, rgb-wallet

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features.

rgb-std rgb?
rgb-wallet rgb?