Attempting to install drupal/kint through composer currently links to drupal/devel, which once provided kint as a submodule. It hasn't been provided for 5 years and no currently supported versions of drupal/devel contain kint.
Due to this naming conflict, drupal/kint now requires installation via the package name drupal/kint-kint.
Devel developers are also perplexed by this: https://gitlab.com/drupalspoons/devel/-/issues/549
composer show -a drupal/kint
Results in:
name     : drupal/kint
descrip. : Wrapper for Kint debugging tool.
keywords : 
versions : 2.x-dev, 2.1.0, 2.0.0, 1.x-dev, 1.2.0, 1.1.0, 1.0.0, 1.0.0-rc2, 1.0.0-rc1, 1.0.0-beta1, 1.0.0-alpha1, dev-1.x, dev-2.x
type     : metapackage
license  : GNU General Public License v2.0 or later (GPL-2.0-or-later) (OSI approved) https://spdx.org/licenses/GPL-2.0-or-later.html#licenseText
homepage : https://www.drupal.org/project/devel
source   : []  
dist     : []  
names    : drupal/kint
support
source : https://git.drupalcode.org/project/devel
requires
drupal/devel ^2
drupal/core ~8.0
Remove drupal/kint metapackage, allow https://www.drupal.org/project/kint β to use drupal/kint.
Root composer.json of kint module for completeness:
{
    "name": "drupal/kint",
    "description": "Kint dumping tool, drupal-specific kint configs, and devel integration",
    "type": "drupal-module",
    "license": "GPL-2.0-or-later",
    "require": {
        "php": ">= 8",
        "drupal/core": ">= 9",
        "kint-php/kint": "^6.0.1",
        "kint-php/kint-twig": "^6"
    },
    "require-dev": {
        "phpstan/phpstan": "^1.0",
        "phpstan/extension-installer": "^1.4",
        "mglaman/phpstan-drupal": "^1.0",
        "phpstan/phpstan-deprecation-rules": "^1.0",
        "drupal/coder": "^8.3",
        "drupal/devel": "^5"
    },
    "conflict": {
        "drupal/devel": "<5.3.0"
    },
    "suggest": {
        "drupal/devel": "Various blocks, pages, and functions for developers."
    },
    "autoload": {
        "files": ["init.php"]
    },
    "extra": {
        "kint": {
            "disable-helpers": true
        }
    },
    "config": {
        "allow-plugins": {
            "dealerdirect/phpcodesniffer-composer-installer": true,
            "phpstan/extension-installer": true
        }
    }
}
Active
1.0
Namespace request