The Steamer is the first unit that I want to add. This bridges the gap between the Galleon (mid-Renaissance) and the Transport (mid-Industrial). The Steamer is available at Steam Power, so it comes right at the beginning of the Industrial Era. I really prefer the short name Steamer over something clunky like Paddlesteamer.
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It's been statted to fit neatly between the Galleon and the Transport, and it also gives an actual transport ship in the Steam Ship category (Galleon is Sailing Ship, Transport is Diesel Ship) and lets you build a semi-modern ship without Oil Products.
Galleon Steamer Transport
Cost 130 200 250
Tech Astro + Nav Cannon Steam Power Automobile
Resources None Coal/Oil/Oil Prod Oil Prod/Uranium
Strength 16 24 30
Move 4 4 5
Cargo 3 4 4
I wonder if you've considered slotting a naval unit in there? I've occasionally griped that there's no steam powered warship apart from the mid 19th century ironclad, and noted that (for instance) WWI navies were mostly steam powered - granted by then the turbine had just been introduced and they were supplementing the burn with sprayed fuel oil. There seemed too big a gap between the 1850-ish and the 1950-ish navies.