Yes, as long as you download the Meross app and log into your account on a mobile phone, you can access your Meross smart home devices. The Meross app can be downloaded on multiple mobile phones.
If you want to share access to your Meross devices with others, there are several ways to do so:
For the Meross app, simply have the other person log in using the same account on their phone.
For Amazon Alexa, you can follow the steps in this article: https://www.pcmag.com/how-to/let-multiple-people-use-the-same-amazon-echo
For Google Home, you can follow the steps in this article: https://support.google.com/googlenest/answer/9155535?hl=en
For HomeKit (HomeKit-enabled devices only), you can follow the steps in this article: https://support.apple.com/en-us/HT208709