For the past 6 months I have been using the RomRider NiceHash integration.
It stopped responding this past weekend, and I have been looking for a alternate, including use of the Home Assistant REST and the NiceHash API.
I came upon your integration, recently added and updated, and installed.

Your integration seems to load (no errors in the interface), unfortunately "No devices or entities"

Here is an output of the log and an error related to the integration...hope it helps

Home Assistant version 2023.6.2

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Logger: homeassistant.components.sensor
Source: helpers/update_coordinator.py:258
Integration: Sensor (documentation, issues)
First occurred: 11:38:16 AM (1 occurrences)
Last logged: 11:38:16 AM

Error while setting up nh_nicehash platform for sensor
Traceback (most recent call last):
File "/config/custom_components/nh_nicehash/coordinator.py", line 37, in fetch_data
totalBalance = json.loads(my_accounts_json)['totalBalance'] | int
~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^
TypeError: string indices must be integers, not 'str'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/usr/src/homeassistant/homeassistant/helpers/update_coordinator.py", line 283, in _async_refresh
self.data = await self._async_update_data()
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/src/homeassistant/homeassistant/helpers/update_coordinator.py", line 242, in _async_update_data
return await self.update_method()
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/config/custom_components/nh_nicehash/coordinator.py", line 103, in fetch_data
raise UpdateFailed(f"Error fetching data from NiceHash API: {e}")
homeassistant.helpers.update_coordinator.UpdateFailed: Error fetching data from NiceHash API: string indices must be integers, not 'str'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/usr/src/homeassistant/homeassistant/helpers/entity_platform.py", line 320, in _async_setup_platform
await asyncio.shield(task)
File "/config/custom_components/nh_nicehash/sensor.py", line 10, in async_setup_entry
await coordinator.async_config_entry_first_refresh()
File "/usr/src/homeassistant/homeassistant/helpers/update_coordinator.py", line 258, in async_config_entry_first_refresh
raise ex
homeassistant.exceptions.ConfigEntryNotReady: Error fetching data from NiceHash API: string indices must be integers, not 'str'