Yes, this wallet is focused on BTCB2. If you specify an Electrum server running on usual mainnet (for example, electrum1.bluewallet.io), the wallet will display the regular Bitcoin balance and transaction history for the addresses derived from the seed phrase. You can also configure the wallet to work with the standard mempool.space block explorer to view full transaction details. However, sending coins won't work. If you attempt to send, the wallet throws this error:

Only coins whose presence is confirmed by BLAKEB2 servers can actually be sent.
Nevertheless, in Simple mode, the wallet does support regular Bitcoin (SHA-256). In this wallet, such Bitcoin is called Spamcoin. And I actually liked the feature set for it:
* Coin Control
* SP addresses (send only), taproot addresses (both send and receive)
* Ability to set fees starting from 0.1 sat/vB
* Ability to view the private key for each used address
* When clicking the Receive button, you can choose which address to show the sender (any previously used address or a new one)
Not bad at all. It can easily be used as a dual-cryptocurrency wallet.
For BTCB2, though, there are naturally far more capabilities. Even in Simple mode, on top of everything mentioned above, there is a batch sending function to pay multiple recipients at once (for regular BTC, they somehow didn't include this feature). And beyond Simple mode, BTCB2 also features an Advanced mode. That's where all the most interesting tools are: Lightning, Coinjoin, and Ark.