This looks like it is available again. You have to backorder but expected to ship (vs just unable to order.) Also have the oscillating tool and reciprocating tool versions available.
https://www.homedepot.c
https://www.homedepot.com/p/Makita-18V-LXT-Lithium-Ion-High-Capacity-Battery-Pack-4-0Ah-with-Fuel-Gauge-and-Charger-Starter-Kit-W-BONUS-Reciprocating-Saw-BL1840BDC1XRJ04/309233804?
https://www.homedepot.com/p/Makita-18V-LXT-Lithium-Ion-High-Capacity-Battery-Pack-4-0Ah-w-Fuel-Gauge-and-Charger-Starter-Kit-W-BONUS-Oscillating-Multi-Tool-BL1840BDC1XMT03/309233778?