Upgrade 2016 Prius base Entune to Navigation

I'm looking to upgrade my Prius's base Entune audio (6.1 in) to Entune Premium - non-JBL (7 in), and I'm wondering if this is worth tackling.

Reasons to not go aftermarket for me
- The bigger higher definition screen is nicer with 7-in screen
- Integration with upper auxiliary display with audio and speed limit read outs is nice.. This is currently unavailable for me with base audio. Will upgrading to premium system even add this? If so, a plus here.
- Personally prefer the OEM fit and feel of headunit versus aftermarket.
- Don't care about Satellite Radio so the deal with antenna replacement is not applicable to me

I noticed Infotainment offered an OEM solution, but quite cost-prohibitive. Ebay gives few appealing options at $200 price bracket.

Some of the threads mentioned a lack of GPS antenna when I do the swap. Can I address this by adding an external GPS antenna easily found on Amazon?

Is it possible in my situation to buy one off Ebay and do a plug/play swap? Thanks!

 

Update: I ended up finding a headunit off of Ebay for ~$200 with Navigation and SD card built in. The headunit I got also came with XM radio which I didn't need (took it out). The headunit was an entire plug and play. Since my base Prius didn't come with antennas for XM or GPS, I got a cheap one off Amazon (search "GPS antenna fakra plug"). Took the plastic connector off with a tab, and inserted the antenna plug into headunit.

Everything works! I got the VIN from the Ebay listing to which the headunit belonged to, and Entune apps got activated and worked. And since my base model car doesn't have JBL, the unit I had to get should also not have JBL since the amplifiers are separated.

Total cost for this swap was headunit ($200) + GPS antenna ($10). The only downside was I was expecting the MID display next to the speedometer to also display GPS and radio functionalities, but looks like nothing comes up. But for $210, this was a very painless upgrade.