In DuckDuckGo, if you search for a currency symbol (I’ve not tried obscure ones) and tap on the ‘Currency’ heading on the right, you get a little converter with one unit of that currency inputted. You could bookmark this page for future reference. Alternatively, you can search for say $17 and go to the ‘Currency’ heading and have that value pre-filled. The rates seem to be from the previous day, so this is for people who don’t need precision and don’t want to install yet another app which costs money…or is free with shitty adverts or uses up space on their old, chock-a-block device.