Jio 5G has started working suddenly from today. I don't know calling Jio helped or it was update to carrier services today.
1. Speeds are decent but not as consistent as iPhone 13 or later.
2. Pixel 6a has tendancy to revert to 4G where as iPhone 13 holds 5G signal far far better at the same place.
3. Signal strength bars always show 50% and it does not have any bearing on speedtest results. I can get 800 Mbps speeds and signal strength will still show poor reception.
4. Vo5G or VoNR works flawlessly with NR Only mode set under *#*#4636#*#*
5. I had to root and edit /data/user_de/0/com.android.phone/files/carrierconfig-com.google.android.carrier-89918740400278732189-2018.xml
and add <boolean name="vonr_enabled_bool" value="true" />
before the </bundle> at the end. This gave me Vo5G option under Sim settings.
All the three work now: 5G data, Vo5G, VoWifi
Overall, I am kinda disappointed with 5G cellular reception and I hope Google boosts signal strength in future android updates because same modem Samsung Exynos 2100
is present in Samsung Galaxy S21 and those phones never had cellular connectivity issues.