The D100 has no map so it would be a long shot for Dynon to ever do anything with it like traffic or weather.
The 396 can display TIS-A traffic from anything that spits out a TIS signal. It is limited to the number of targets it will display.
As far as I know, there is no other option for weather on a 396 other than XM.
To comply with ADS-B out requirements of 2020, you will need either a UAT or a 1090ES transponder with an approved precision position source feeding it your position. If you go with the UAT option, keep in mind that it has limitations on it for region, speed and altitude and it must have the same squawk code as your transponder. This typically means you need a UAT and transponder that are capable of talking to each other.
Being in compliance does not require that you have any weather or traffic display capability. All the FAA wants is that you send them the info they want with ADS-B out. They do not care if you can use the free weather or traffic or not.