ASTRONEER

In order to fit more than one person in a shuttle, you need to mount a rover seat to the shuttle, as only one person will fit in the cockpit. You can mount one in the small shuttle in the small bay meant for an oxygenator (this is how I did it), or you can wait until you have the medium shuttle and mount a rover seat in its cargo bay.

In total, the bare minimum you will need is:

-A small shuttle (constructed from the large printer, 2 aluminum)
-A rover seat (2 compound, although you can also commonly find them in wrecks)
-A solid-fuel thruster (1 aluminum, 1 ammonium)

Or in total, 3 aluminum, 2 compound, 1 ammonium.

You can find laterite, the ore used to smelt aluminum, underground. It's extremely common so you should have no trouble at all finding it. Ammonium will potentially be tricky to find, it is on the surface of Sylva but not in large quantities. It's more common underground, increasingly so the further down you go, so if you're really struggling to find ammonium, just make yourself a bunch of tethers and start digging down.

And finally, a word of advice: if you have the resources, construct a second solid-fuel thruster for safety's sake. I had a bug where my shuttle could not land where I had selected on Desolo, forcing it to immediately take back off and using up the engine. This led to me being stranded there for a good long while while I slowly built back up enough to build a new engine there and get back home.