The only thing I would add to this thread is perhaps to consider the "glass" top from Visium. See
Transparent Roadster Top
and
Seeking long term feedback from Visium owners.
Must-haves, as noted by others, are the two CAN adapters (JR and SR). The Roadster pre-dates the modern EV infrastructure - it's the car that effectively started it all - and these two gems make the car as able to participate as most, with only the exception of the lack of DC charging. In practice, I have found that to be an annoyance, but it hasn't prevented me from trips that DC charging might have been otherwise been useful for. Just took a bit more planning. I got lucky, as my car came with the upgraded headlights and PEM fan, and I'm on the list for the new brakes and rotors.
Finally, the in-dash unit. {sigh} I, too, have found it less than brilliant, but to be honest, I do still use it. All of the other options seem to have some fatal flaw, such as the blocking of the vents, etc., though I am still keeping an eye out for a worthy single-DIN replacement. In the mean time (and likely forever), Bluetooth to my phone lets me listen to music and podcasts, and some of my library that came on CDs even made it to the unit's hard drive. Phone calls get answered, and I can yell at whoever is calling that I will call them back. (The car's BT mike is horribly placed, so all the other person hears is noise until you pull over and talk in quiet.) Even the Nav part gets used. Yes, the maps are several years out of date, but still useful when I find myself out of cell coverage and needing some basic orientation. I sometimes let Google Maps and the Nav unit arm-wrestle for the latest info and best routes, and it's easy to see the miles remaining to destination and compare that with the VDS estimate on remaining range.. Nerdly entertaining, if nothing else.
I have tried replacing the rear view mirror with one that has a display built in, but the resolution was no better than the in-dash unit, and with the glare from the windshield behind it, harder to see. Also worried about using it at night, because it might be considered by the local police as viewing a movie.
Oh - do get a windshield mount for your phone. I found the normal position down on the center console difficult to view, and the modern phones are just too wide to sit there as originally intended. The one I found (
https://www.walmart.com/ip/Nekteck-...eld-Mobile-Phone-Mount-Holder-Black/145948215) has a suction back, and mounts nicely in the lower left corner of the windshield. I run a USB cord from there to a small 12v USB power gizmo in the accessory outlet under the console.
Enjoy your new car, and welcome!