To check the storage value of another SC you would create a callable function (endpoint or view doesn't matter) and call that from your contract :) can i assure that calling a function of another SC in the same shard and retrieving result is sync process? can i get SC result without using callback function?

If you are 100% sure that the contract is in the same shard (and remains there ????) then you can use execute_on_dest_context to directly get the result without having to worry about callback functions :) However if you are utilizing third-party contracts than it would be more safe to use the normal async calls as that guarantees that it's working even after adaptive sharding is active :) But you will have to use callback functions, afaik :)