Hi I am actually on testnet too and have found this address where you can request 100m testnet ADA for the pledge. I did it and it works well, just need to wait few days.
They are also asking to send the funds back when you don’t want to participate anymore on testnet.
Thanks for this info from TOPO Stake Pool / telegram group.
Regarding some tool to check testnet pools, i don’t know and also looking for that. Let me know if you find any tool for that. You can check your relay(s) is part of the network here:
https://explorer.cardano-testnet.iohkdev.io/relays/topology.json