I agree with you that the GUI does that for me, but I need to have a dashboard with BTC holding, ETH holding etc... I need to be able to get all the info from somewhere... so I was wondering, if I include one of the many Addresses of my wallet, somehow could I "get also the other addresses associated with the same wallet (read only)...
is it feasible?
You can't. Having an address will not reveal the other addresses generated with the same seed. The only way for you to obtain all the addresses within the wallet is by using the master public key to generate them all. If you were to disable change address, all your Bitcoins would be consolidated within one address, provided that you also only use that one address. This would greatly affect your privacy however,