Are there functioning staking pools in the testnet?

Hi Dima

If you are looking to use CNTools then you should look at the post that @Alexd1985 did names

How to set up a POOL in a few minutes - and register using CNTOOLS

You can go to the Cardano Github pages

https://github.com/input-output-hk/cardano-node/tree/master/doc/getting-started

Another good resources the Coin Cashew site

Finally another resource is

https://cardano-foundation.gitbook.io/stake-pool-course/

All of them include input on the testnet also

Kind Regards
Shad