Not used parts but consider Gevenalle shifters for either set up. They are friction for front shifting so double or triple are not an issue and are available with rear indexing in 9, 10, 11 and 12-speed formats, both road and MTB. They are as convenient as "brifters", less expensive than most, very durable and much cheaper to upgrade if you, say, want to go from 9 to 10-speed later on. I have them on three bikes, all 3x10, and they work wonderfully.

As to triple cranks, the most recent Shimao good one was the FC-5703 that came 50/39/30 but, having a 74mm bcd granny BCD, it will accept down to a 24T chainring. A 3x9 with 50/39/24 chainrings and a 12x30 cassette will cover a large overall gear range with out big gaps in the gearing.

If you go for a double crank, try to find a gravel or MTB model geared 46/30 or similar and match it with a big big cog like a 34T or more.