You can clone this repository using:
git clone https://github.com/ilkermanap/redbelly-utils
checksync.py first looks at the Redbelly rpc at https://rbn-gcp-australia-southeast1-a-0-b-v2.devnet.redbelly.network:8545 and then find outs the block height in a given rpc.
ilker@t440s:~/src/redbelly-utils$ python3 checksync.py https://example.mynodes.xyz:8545
--------------------------------------------------
URL : https://rbn-gcp-australia-southeast1-a-0-b-v2.devnet.redbelly.network:8545
Block Height : 41852
Sync Speed : 0.0005401109176198041
Time to sync : 0:00:00
--------------------------------------------------
URL : https://example.mynodes.xyz:8545
Block Height : 9676
Sync Speed : 0.3640347936808723
Time to sync : 1 day, 0:33:07.155729
Your node https://example.mynodes.xyz:8545 is behind 32176 blocks from https://rbn-gcp-australia-southeast1-a-0-b-v2.devnet.redbelly.network:8545