The "drop-in" requirement is key. It does make sense to want a ready-made configuration of cells, packaging, and BMS, but the problem is that for there to be a commercial product, there needs to be a common configuration to fit.
The problem with a 12-volt configuration in an EV is that you end up with many (ten in this case) of these units, probably without a coordinated BMS. Technically it can certainly work (they're just 4S LFP modules), but since these are usually made for applications which only need 12 volts, they're usually not designed to be connected in series in a coordinated way.
I've seen at least one supplier offering a single unit to replace the entire 48-volt set of lead-acid batteries in a golf cart, which is practical because there is a common configuration to replace: they're essentially all 48-volt nominal, consisting of six 8V or eight 6V GC2-sized batteries in a row. The advantages of a single unit over combining smaller units include avoiding the need for parallel connections (such as 4S2P of 12-volt units), reducing cost and complexity of packaging a wiring, and including on lithium-specific charger in the package.
Completely drop-in doesn't seem likely to work out reasonably for a 120-volt conversion from lead-acid. The most practical might be a combination of some reasonable number of pre-assembled modules (with BMS components) plus a central BMS master and charger. Chevrolet Volt modules and BMS are potential components for that approach.