ios or android for OBD1 monitoring

I'm doing an LT1 swap into a 79 Malibu wagon. I wont have a mechanical drive for the stock speedometer so that will be out of service. A while back I saw a guy who had a smaller android tablet that he had connected to the diagnostic port on his 94 Z28 LT1. He said he could monitor in real time the info from the PCM like speed, rpm and other operation data. I would like to get this ability.

Are there free apps that can do this on either android or iOS? If so what is the app name(s)? What cable(s) do I need?

I need something that works with 1994 OBD1 LT1

I have a spare iPhone 6s I could use if possible, or, I'm willing to pick up a used android device if that's better. What in your opinion would be a low cost android device that would work for this?

I know there are alot of questions so I don't expect all of them answered, but any insight would be appreciated.

Thanks

I'll apologize in advance for not answering your actual question, but if you are interested in alternatives,
I use a mechanical speedo drive from Dakota Digital for the EFI conversion in my '70 Pontiac. I wanted
to keep the original speedo working, and this unit has been great:

https://www.dakotadigital.com/pdf/ECD-100.pdf

Looks like it may have been superseded by a newer model though:

https://www.dakotadigital.com/pdf/ECD-200BT.pdf

They're a little spendy, so it really depends upon how much you want to keep your original dash
looking and working like stock.

-Scott

Nice piece from Dakota Digital there Scott! Thanks for sharing. It's a bit too expensive for the current budget though.

you probably want aldldroid, it's on the app store, it's about the only thing that's going to work with the ol' aldl bus on a modern tablet or phone

keep in mind by replacing the speedometer that you're losing the odometer too, depending on where you are and what you plan on doing with it, this could give you legal issues with insurance or inspections. if you get a jerk cop he might pull a vehicle inspection ticket on you if you get pulled over speeding and he realizes you have no working factory looking speedometer

if you wanted to, you could always just get a gps speedometer app for your phone however that's only accurate on a flat surface

Ok I’ll get a cheap used android Galaxy tablet. What cable do I need and what app? I searched a bit and mainly get returns on obd2 stuff.

netbooks like the samsung n 140 work on windows and have an usb connector!