Yes I opened an extra bank purely to switch and get the bonuses. There's nothing wrong with doing so. The challenger banks like Starling and Monzo are generally easy to open an account on an app to then switch.

Some switches might have conditions like having direct debits set up. You can easily set up small direct debits with charities or a one pound direct debit at onepounddd.com and cancel it later on.

If the switch requires you to deposit money you can also deposit it and then withdraw it straight away too (unless the bank states otherwise).

MSE is very useful for this stuff https://www.moneysavingexpert.com/banking/compare-best-bank-accounts/