The temp IC is not included (along with the requisite capacitors for that IC) as temperature sensing is not supported in the software yet. This will be added at a later date.
LCSC BOM does NOT contain a battery holder. The cheapest place I can find these is Digikey (or very close), with Aliexpress winning for 50 pieces or more.
Building one board from Digikey and OSHpark will cost about $27 plus shipping from Digikey. Building 10 boards from LCSC and jlcpcb, plus the battery holder from Digikey, will cost about $36 plus shipping from Digikey.