The Eclipse IDE is a modern and open IDE for cloud and desktop. The Theia IDE is based on the Theia platform. The Theia IDE is available as a downloadable desktop application. You can also try the latest version of the Theia IDE online. For more details, see the Readme below.
Since Theia 1.50.0, and https://github.com/eclipse-theia/theia/pull/13708 was merged, it is now possible to remove the workaround for the Environment variable server located here: https://github.com/eclipse-theia/theia-blueprint/blob/e103d544a33fe0bcb13bf41ca28c8d2e2d775015/theia-extensions/product/src/node/theia-ide-variables-server.ts. The THEIA_CONFIG_DIR env variable value can be directly added to the package.json of the application.
The hard coded path in theia-electron-main.js should be also removed. The plugins located in theia-ide (or as indicated by THEIA_CONFIG_DIR environment variable) will be deployed by https://github.com/eclipse-theia/theia/blob/03cdc9939e6e73c2213366695cd83f52549c5b68/packages/plugin-ext/src/main/node/plugin-theia-deployer-participant.ts#L28.