You can still use your current setup through Sparrow and don't need to change HWW. In fact, you can set up a watch only wallet of your current setup with Sparrow by importing the xpub if you're just curious about how the client works (no need to connect the Trezor). The main benefits with Sparrow over Trezor Suite is that you can use it with your own node/electrum server (as well as better ui/ux IMO). If later on you decide to use Sparrow as your main client, you can use the watch-only wallet to create transactions and it will ask you to sign with your Trezor.