I use an old-school jump starter (doesn't turn itself off) that has a 12V cigarette lighter socket as a memory saver on OBD1 vehicles. If the car's cigarette lighter stays on when the ignition is off you can run a cable with cigarette lighter plugs on both ends between the jump starter and the car.

If the lighter socket in the car is not powered with the ignition off I use a similar cable but with alligator clips on one end that I can clip to convenient 12V and ground connections in the engine compartment.

I have never heard of a memory saver that has OBD 1 support. I wouldn't personally recommend it anyway as they kinda don't do much of anything besides put more failure points on anything other than a battery replacement. I think there are a couple videos to make your own online but I would highly recommend against it again.