Unfortuantely I had the same issue during the summer when I planned to buy a battery to compliment my FT-818. Supply and demand has seriously been skewed since the up take of hobbies during lockdown and the reduction in manufacturing!
I settled on a GNB 6200mAh battery from HobbyRC.co.uk (https://www.hobbyrc.co.uk/gnb-6200mah-2s-90c-hardcase-lipo-battery)
I couldn’t be happier with my purchase, the battery easily lasts most of the day, has an indestructible hardcase (not many batteries have hard cases), small dimensions, cheap and the delivery was lightning quick. I can’t help but feel that HobbyKing batteries are rather a rip-off after my experience!
As for rods, I’ve also had a good experience with Decathlon Lakeside series travel rods (https://www.decathlon.co.uk/p/lakeside-1-travel-400-telescopic-still-fishing-rod-4m/_/R-p-102580). I purchased the 6m version but managed to snap off the top meter by hauling a rather heavy dipole centre in the air. They pack down to less than the length of my arm! I can snuggly fit inside my small capacity backpack. Availability fluctuates but they often are not out of stock for more than a few days.
Beware unless you shell out on thick walled telescopic poles then you will most likely get the full 6m/7m extension unless you have a particularly lightweight antenna.