The best 1s batteries seem to be the ones with the Ph 2.0 connector attached to the body of the battery instead of on a short lead. My Mobula 6's leads are
HV LiPo Battery 3.8V 330MAH 1S 90C/180C With PH2.0 Connector Cabled For Mini Quads FPV DRONE Emax Parts
Tinyhawk | Emax USA
Easiest and cheapest way to reduce battery sag on tiny whoop: hot glue. Got extra 30-40 seconds more flight time : r/TinyWhoop
Amazon.com: NIDICI 20pcs(10 Pairs) 1S Charger 3.7v Charging Cable Male & Female for 1s Lipo Battery RC Quadcopter Drone Multirotors : Toys & Games
Amazon.com: elechawk 10 Pairs 2.0mm Spade 2P Cable 8cm Lead Plug Connector Male and Female for 1S Lipo Battery Charging Drone Syma X5C X5SW SNAPTAIN S5C : Toys & Games