I have a single screen Dynon HDX in my RV-14, but the Autopilot is incapable of flying any approaches without a secondary (certified?) GPS source. There also is no nav/com unit for glide slope & ILS information such as the Garmin SL30. Is there one unit for all of this, or separate units only?
What equipment would you recommend to accomplish this?
On a side note, I can't believe equipment as nice as the HDX is that far behind the curve. The 12 year old G1000 can do all of this.
You have some misinformation. The person that is behind the curve was your panel designer. If that was you, I apologize for being so blunt.
What you want to accomplish is very possible with the HDX, you just need the appropriate avionics and a good panel design. The Skyview installation manual documents the requirements pretty well.
I see that you are in Florida. I would go pay Jesse Saint a visit. I'm sure that Jesse will be more than happy to meet with you and discuss your situation. His shop can assist your with the installation as well.
If you want to fly GPS approaches, then yes, you'll need a GPS that meets the TSO certification for approaches. You'll also need the approach data, which you can only obtain and use with one of the certified GPS units. My recommendation would be an Avidyne GPS, because there are more third party integrations available. Garmin's will work too, but their interfaces are all Garmin proprietary for things like flight plan loading to the EFIS, remote control via the EFIS, etc. If you purchase the GPS unit that also have a comm and nav radio, you can solve all your issues with a single box.
With the HDX you will need to have the Dynon autopilot solution, since Dynon EFIS doesn't fully integrate with the third party AP heads. The Skyview EFIS can't translate the appropriate commands for the ILS and VOR approaches to a third party AP head, such as a Trutrak Vizion. However, it will to the Dynon AP function built into the EFIS.