Obviously I’m not expecting this to be a full sat nav like a Garmin or something like that, but is it possible to get a small sat nav system for a bike (bicycle, not motorbike).
There are two routes you can go down for a cycle computer/sat nav - basic or feature-packed. The Garmin Edge 25 is a basic, affordable (and tiny) bike computer that provides simple stats such as time, distance and speed without the fuss or expense of a more advanced model. Dig deeper, and you’ll find more advanced features like live tracking and turn-by-turn guidance for routes downloaded from your computer. It has ANT+ capability, too, allowing you to connect heart rate or cadence sensors. A slightly pricier (£20 or so) alternative you're less likely to have heard of is Beeline, a simple and attractive bike computer that allows you to input a destination via the smartphone app for turn-by-turn directions to your destination. We're rather taken by the Beeline. Serious cyclists will want more features, but it's a great gift for the casual rider. Beeline offers a great battery life and it creates opportunities to explore areas.
When it comes to more advanced cycle computers, our two favourites are the Mio Cyclo 210 and Wahoo ELEMNT Bolt - which are priced identically (at the time of writing). The Mio is an entry-level unit that features a 10-hour battery life, Strava connectivity and a Surprise Me feature — which can create its own routes depending on how far or for how long the rider wants to cycle for. However, there’s no ANT+ connection so it can’t connect it to a heart rate monitor, nor is there Bluetooth. The ELEMNT Bolt can be an easy way of accessing route information and finding out just how well you’re performing. The Bolt can also pair directly with ANT+ sensors, like Wahoo's TICKR Fit heart rate monitor (as well as power meters, speed sensors, cadence sensors etc). If the recipient you have in mind is a gadget geek and a keen cyclist, the ELEMNT Bolt is made for them. If they're less handy with a smartphone and want smarter-looking navigation — the more affordable Mio Cyclo 210 would be our recommendation.