Hello,

I am planning a trip on my roadbike, and last time I have done a trip I was super annoyed using my phone as my GPS.
I couldn't see anything because of the sun, so I had to stop to check google maps and try to remember the next 5/6 turns, then stop again, then realized I messed up and go back 5km, etc..
My smartphone doesn't work very well anyway.

I'd like to know the options I have to get directions on a bicycle computer, but my budget is pretty low, sub 100€ pretty much.
I've seen some lezyne GPS units or Garmin eTrex 10, but the first one seem to depend a lot on my smartphone (that I would like to avoid) and the second one seems to have lots of great features but the map seems too basic and I'm scared it won't have all the roads I need, making me missing the quickest road to get from point A to point B.

Thanks

Unfortunately this website is having some troubles right now in providing maps over large areas. Note the red text at the top of page.
Free worldwide Garmin maps from OpenStreetMap

In the past, that has been my go-to source for routable Garmin compatable cycling maps. I found I could get a pretty big area of coverage and keep the map size to less than 1.5 gb. Larger than that and sometimes my Garmin did not like the map.

If you are in Europe (your budget is in Euros, so I assume you are), this may be a better map source:
Europe - OpenFietsMap

I have not used the Etrex 10, but the other Garmin units that I have used allow me to download a map on sources such as the above and install it directly on the Garmin. My Garmins allow me to put a micro SD card in them for more memory, I use 32 gb cards for that purpose.

These big files are often sent in zip file format, need to unzip them after download.

With my Garmins, I can load multiple map and select which map I want to use at that time. Sometimes I use the cycling map from the first link above, sometimes instead I use a topo map, sometimes use a street map intended for automobiles.

Some GPS units can fall out of the handlebar mount, if you can use a cord as a lanyard on the GPS, it is a good idea to strap that to the handlebar so if the GPS falls out of the mount, it stays with the bike instead of crashing on the pavement.

Good luck.

If you're mostly riding in places where there's cellular data service , (and if Elon Musk gets his way, that will soon be almost everywhere on Earth), you can use map apps and/or bike computer apps on a smartphone or small tablet. You'd also have the flexibility of accessing real-time weather apps, etc. I've been using the "Urban Biker" app for about 4 years now, and I've never felt the need to buy a Garmin.

A lezyne super GPS has been flawless for me for 4 years now.
You use your phone to send the route to the GPS unit and that's it. No phone use any longer.

All gps units need to get the route info somehow.

sorry to say, but your desired features are outside your budget...