An Eastern Beaver PC-8 is probably your best bet, unless you're going to go whole hog and buy one of those computerized power distribution blocks that don't use fuses and instead use electronic circuit breakers. Those are smaller than the PC-8, but way more expensive.
This is the page for the relevant parts for your bike: https://easternbeaver.com/Main/Bike_...om/vstrom.html
The PC-8 allows you to have different power options. You can make everything switched by running through a relay, or everything "always hot" by skipping the relay and running directly from the battery, or even a combination of the two; the PC-8 has the option of having two circuits always hot and the rest switched. The PC-8 gives you some flexibility, too; you might later decide to add other accessories like heated grips or additional power outlets, and the PC-8 has room for this expansion.
The nice thing about the PC-8 is that Eastern Beaver makes it plug and play. You don't need to splice wires or attach quick connects, and the instructions are pretty clear. I'm not an electronics guy at all, and I installed both the PC-8 and their headlight relay with no issues.
There are other power distribution blocks besides the PC-8; Blue Sea makes a nice one, as does CenTech. But for total ease of installation, I don't think you can go wrong with Eastern Beaver.
The simplest way is to wire the GPS mount directly to your battery with an in-line fuse, and that's fine if that's the only accessory you'll ever install. Installing a fuse block is kind of planning for the future. Keep in mind that there can be a parasitic drain from accessories attached directly to a battery, though, so if your bike sits for long periods of time with something like that hard wired to the battery, there's the potential for your battery draining.