One thing to keep in mind: rental companies require a guarantee that you are good to cover all costs. This is your rental sum, a full tank of petrol plus any costs that are not insured (the so called non-waivable excess). As long as you're able to pay full upfront for this then you should be fine, although cash shall not work. This means that a debit card most likely will work, but that the entire sum (!!) will be deducted before you take the car and the remainder (minus the rental sum and potentially the gas) will be returned to you after you return the car. This may take several days to a week. During this time the money will not be in your bunq account. Also there may be additional requirements to make a Debit Card work. For example, check Hertz page on this for rentals in the US (LAX Airport):
https://www.hertz.com/rentacar/reservation/reviewmodifycancel/templates/rentalTerms.jsp?KEYWORD=PAYMENT&EOAG=LAX
The same btw applies for hotels and petrol stations. I've seen funds to be debited from my account at a petrol station (in the US) and the remainder was credited back in a day or 2. If you have a lot of this it might cut a serious hole in your balance.
My advice for longer trips would always be to obtain at least one true Credit Card with sufficient credit. For shorter trips a debit might be ok, but check in advance with your rental company. And btw: Tenerife is very nice, need to go back there once. Many great places to eat, but please please please: avoid Playa de las Americás unless you fancy drunk British and Russian teens ;-)