Learn Dutch: Ik onderzoek in hoeverre deze onbeperkte databundel voordelig is. - I investigate to what extent this unlimited data plan is advantageous.

The phrase in hoeverre (to what extent) introduces an indirect question. Indirect questions function as subordinate clauses, meaning the conjugated verb (is) must be pushed to the very end.

Does voordelig just mean "advantageous" in a general sense here?

While it translates to "advantageous", in the context of subscriptions or a databundel (data plan), voordelig specifically implies it is cost-effective, cheap, or a good deal for your wallet.

Why is there an -e at the end of onbeperkte?

Because databundel is a de-word. When an adjective comes before a noun with de, deze, or die, it gets an -e ending. The word deze right before it is a helpful hint that you need the -e on onbeperkte.

Could I use the verb uitzoeken instead of onderzoeken here?

Absolutely. Ik zoek uit in hoeverre... (I am figuring out to what extent...) is very common in spoken Dutch and sounds a bit more casual than onderzoeken, which leans more towards formal research or a thorough investigation.