quick answer, there is no test-net environment for @wallet at this moment.
But if you want you can use @CryptoBOT / https://t.me/CryptoTestnetBot to test out.
I wanna build a ton dapp on tg bot, but I cant find the way to switch net work in the official wallet bot.
This is the code I forked.
https://github.com/ton-connect/demo-telegram-bot
quick answer, there is no test-net environment for @wallet at this moment.
But if you want you can use @CryptoBOT / https://t.me/CryptoTestnetBot to test out.