Here is 2.0 support for Teamspeak Group Integration: https://github.com/Frozen-byte/nodebb-plugin-teamspeak-verify

not yet perfectly documented and code is a bit vintage, but at least it's working

Thank you! The Fork from @baris is what I need.
Do I have to build the fork inside the docker? Since it's not setup with dev-packages, I try to avoid this kind of tinkering.

I have trouble getting the package built inside the docker:
npm i "https://github.com/barisusakli/nodebb-plugin-calendar/tarball/main"
npm activate nodebb-plugin-calendar
./nodebb build
fails with the following error:

node@42ab625bf06d:/usr/src/app$ ./nodebb build
  started
2022-05-21T12:52:34.420Z [4567/2257] - warn: [plugins] File not found: /usr/src/app/node_modules/nodebb-plugin-calendar/build/bundles/ (Ignoring)
2022-05-21T12:52:34.421Z [4567/2257] - error: [build] Encountered error preparing for build
TypeError [ERR_INVALID_ARG_TYPE]: The "path" argument must be of type string or an instance of Buffer or URL. Received undefined
    at Object.stat (node:internal/fs/promises:660:10)
    at processDir (/usr/src/app/src/plugins/data.js:102:36)
    at async Promise.all (index 0)
    at async Data.getStaticDirectories (/usr/src/app/src/plugins/data.js:120:2)
2022-05-21T12:52:34.422Z [4567/2257] - error: [build] Encountered error during build step
TypeError [ERR_INVALID_ARG_TYPE]: The "path" argument must be of type string or an instance of Buffer or URL. Received undefined
    at Object.stat (node:internal/fs/promises:660:10)
    at processDir (/usr/src/app/src/plugins/data.js:102:36)
    at async Promise.all (index 0)
    at async Data.getStaticDirectories (/usr/src/app/src/plugins/data.js:120:2)
2022-05-21T12:52:34.422Z [4567/2257] - error: TypeError [ERR_INVALID_ARG_TYPE]: The "path" argument must be of type string or an instance of Buffer or URL. Received undefined
    at Object.stat (node:internal/fs/promises:660:10)
    at processDir (/usr/src/app/src/plugins/data.js:102:36)
    at async Promise.all (index 0)
    at async Data.getStaticDirectories (/usr/src/app/src/plugins/data.js:120:2)

Currently setting up a v2.0 nodeBB Forum.
I was confused as nodebb-plugin-calendar was listed as compatible here.

What am I doing wrong? Do I have to use any special branch/fork?
Installing the @latest ("nodebb-plugin-calendar": "^1.1.3") leads to this error:

opt_nodebb_1  | 2022-05-20T13:13:30.946Z [4567/357] - info: Initializing NodeBB v2.0.0 *snip*
opt_nodebb_1  | 2022-05-20T13:13:32.447Z [4567/357] - info: [socket.io] Restricting access to origin: *snip*
opt_nodebb_1  | 2022-05-20T13:13:33.053Z [4567/357] - warn:    [plugins/nodebb-plugin-calendar] The plugin.json field "library" is deprecated. Please use the package.json field "main" instead.
opt_nodebb_1  | 2022-05-20T13:13:33.054Z [4567/357] - warn: [plugins] Unable to load library for: nodebb-plugin-calendar
opt_nodebb_1  | 2022-05-20T13:13:33.062Z [4567/357] - error: ReferenceError: define is not defined
opt_nodebb_1  |     at Object.<anonymous> (/usr/src/app/public/src/modules/translator.js:5:1)
opt_nodebb_1  |     at Module._compile (node:internal/modules/cjs/loader:1105:14)
opt_nodebb_1  |     at Object.Module._extensions..js (node:internal/modules/cjs/loader:1159:10)
opt_nodebb_1  |     at Module.load (node:internal/modules/cjs/loader:981:32)
opt_nodebb_1  |     at Function.Module._load (node:internal/modules/cjs/loader:822:12)
opt_nodebb_1  |     at Module.require (node:internal/modules/cjs/loader:1005:19)
opt_nodebb_1  |     at require (node:internal/modules/cjs/helpers:102:18)
opt_nodebb_1  |     at Module.require.main.require (/usr/src/app/require-main.js:8:10)
opt_nodebb_1  |     at Object.<anonymous> (/usr/src/app/node_modules/nodebb-plugin-calendar/src/lib/index.ts:20:38)
opt_nodebb_1  |     at Module._compile (node:internal/modules/cjs/loader:1105:14)
opt_nodebb_1  |

Would love to see nodebb-plugin-steam-sso support. I think the newest one is: https://www.npmjs.com/package/@gruppe-adler/nodebb-plugin-sso-steam-v2