> +(define llhttp-6.0
> +  (package
> +    (inherit llhttp-bootstrap)
> +    (version "6.0.0")

Instead of defining a package variant of llhttp-bootstrap, why not just
update 'llhtp-bootstrap', to keep things simple by just having the
latest version of llhttp in Guix?

> +(define-public node-16.1
> +  (package
> +    (inherit node-lts)
> +    (version "16.1.0")

Likewise.

(Also, how come that the LTS version in Guix (14.18.3) is newer than
the regular version '10.24.1'?)

Greetings,
Maxime.