Hi Pelt,
First of all welcome to this forum!
For clarification I have never owned a Garmin device I do know that it offers a lot of options besides the navigation function too. Via the link underneath I have seen it should be possible to show some key metrics related to the Levo as well:
Ebike Field - Garmin app ~ UPDATE: New Diagnostics app - EMTB Forums
I decided not to buy a Garmin as the BV6000 (or a different cheap Android phone) in combination with BLEvo will cost you approximately 1/3 of the price. But here price is certainly not leading. You will notice also the screen is bigger of the BV6000 and the combination with BLEvo it's a very powerfull device. BLEvo can offer, according to my opinion at least, everything what the Garmin is capable of but next to that it's offering much more features and benefits for example like the smart power functions. It will let you enjoy dynamic support based on leg power and/or hear rate. I suggest that you download the BLEvo manual which will offer you a good insight in all the added values.
I must need to make one correction. I think Garmin will offer you navigation to a specific address too. BLEvo will not (yet) do that. This is depending on Paolo where we should understand BLEvo is his hobby. You can still buy a Garmin of course but I assume when you go riding you will bring a phone with you too. Even if your Garmin is on the handle bars and your phone with BLEvo running is in your pocket or backpack, you can enjoy the smart power functions.
If I may suggest, I would buy BLEvo for only €9,99 and then first test how you like it on your normal phone. If you like it, I would buy a cheap Android phone like the BV6000 and just use it as a display when riding. If you don't like it I would buy an expensive Garmin and then depending if you like to use the smart power functions of BLEvo or not, you may have lost €9,99 and @PaoloBLEvo will be happy that he can buy some excellent Belgium beers.
Let me add one more thing...Garmin is not-no one-able to show all the informations regarding your Levo like power, cadence, battery. It's true that Garmin is some way is more accurate, thinking of %slope, the total rise, and with Garmin you can have the navigation. I am a garmin owner for years, an these are my personal plus and minus over this version of blevo:
PLUSEs
-maps, in particular the openmtbmaps not yet available with blevo
-calculations of %slope and trip overall rise
-integration with basecamp
-battery (with stilus)
-IP
MINUSEs
-plenty of bugs
-expensive
-display
-slow
-connectivity
For BV6000+Blevo current android version:
MINUSES
-Maps (I don't like 4umaps, too much low resolution)
-Calculations of %slope and rise not very much accurate
PLUSES
-Display
-Battery
-Connectivity
-Sensors Turbo Levo
-Speed
-Operating System
-SMART POWER & HR
-Open and expandable
-IP
-The software is continuously maintained and improved