MyGet is described as 'Create NuGet feeds, npm, Bower, Maven, PHP Composer and Vsix repositories with your own packages and those from other upstream package sources such as NuGet.org, Npmjs.com, Maven Central or Packagist.org'. There are three alternatives to MyGet, not only websites but also apps for Linux, Self-Hosted solutions and Windows. The best alternative is Bintray. It's not free, so if you're looking for a free alternative, you could try ProGet or SlimGet.
Bintray is a social platform for developers to publish, download, store, promote, and share open source software packages. With Bintray's full self-service platform developers have full control over their published software and how it is distributed to the world.
Consistency, continuity, compliance – all in one centralized universal package manager with ProGet. ProGet servers as the organization central repository, allowing the enterprise to store all your important asset in one place.
SlimGet is a lightweight implementation of a NuGet and symbol server, powered by ASP.NET Core 2.2, designed to be ran in Docker. It's the software powering the developer's NuGet feed at nuget.emzi0767.com.