Magpul mags don't look like they have enough heft to drop free and ETS mags seems to be a crap shoot.

So what about floorplates?

I usually upgrade my floorplates on pistols and especially want to in this case as the cutout on front leaves a tiny bit wanting for pinky purchase.

What are my options?

I don't necessarily need more rounds, but wouldn't mind them.

Maybe a glock 17 mag with something on it?

Help!

Try a TTI + baseplate.

My magpul mags drop free just fine.

I use the standard Glock + mag extensions they work great, cheap, and give me 1-3 extra rounds depending on the spring tension.  I notice as I get to the point of being able to put 20 rounds in the mag it let me know the magazine spring is nearing time for replacement.  It will work for awhile at 20 rounds then stop locking the slide back then I put extra power springs in as replacement and then it only is +1 till the spring loosens up then they are +2 again.

Magpul and ETs drop free just fine on my gen 5 G17

I use Tango Down Vickers Tactical Floor Plate for Glock on my G19 Gen 4 mags with good results.  They are available in a variety of colors - blue, black, hi vis orange,  and a few earthy tones.  They make grabbing the mag floor plate by the sides much better/easier giving you more solid purchase.  I use orange for most applications but use black for CCW mags.

I have heard that Gen 4 G19 mags will work in G5 pistols.  I don't know if these floor plates will fit a Gen 5 G19 mag though...  If they don't, I'm sure they will make a Gen 5 version in the not so distance future...

Any Glock 19 or 17 magazine will work in the Gen5.  The mag bodies are exactly the same, the follower is the same but orange, the floorplate has a little lip at the front.

They did the cutout on the grip and the lip on the mag because you can't grab the side of the mag very easily because of the flared magwell.  I think a Tango Down floorplate would be right at home on a Gen 5.