Batteries - I'd stick with Canon, model is LP-E17
My second choice would be Watson brand
Canon does not make a battery grip for this body, but vello, neewer and jupio do.
Other power options include a USB-C PD.
No camera battery regardless of brand, type etc should be left plugged in indefinitely.... waiting to be used.
Bay Area - CA
~R5 C (22.214.171.124) ~RF Trinity, ~RF 100 Macro, ~RF 100~400, ~RF 100~500, +RF 1.4x TC, +Canon Control Ring, BG-R10~DxO PhotoLab Elite ~DaVinci Resolve ~Windows11 Pro ~ImageClass MF644Cdw ~Pixel6 ~CarePaks Are Worth It
07/31/2023: New firmware updates are available.
05/31/2023: New firmware updates are available.
05/18/2023: New firmware updates are available.
04/20/2023: New firmware version 1.4.1 is available for EOS R3
03/30/2023: New firmware updates are available.
2/07/2023: New product announcements!EOS R8 EOS R50RF-S55-210mm F5-7.1 IS STMRF24-50mm F4.5-6.3 IS STMRF15-30mm F4.5-6.3 IS STM