Macau has three main mobile operators: CTM (Companhia de Telecomunicacoes de Macau), China Telecom Macau, and Smartone Macau. HelloRoam eSIM plans connect via partner networks with 5G and 4G LTE coverage across the territory.
Macau is so small that coverage is essentially uniform across the whole territory. The Macau Peninsula, Taipa Island, Cotai Strip, and Coloane all have excellent 5G and 4G signal. The casino resorts on the Cotai Strip have indoor coverage throughout. The historic center of Macau, the Ruins of St. Paul, Senado Square, and Coloane village all have strong outdoor signal.
Note that Macau uses its own mobile network separate from mainland China, so a Macau eSIM does not work across the border in Zhuhai or elsewhere in China. If you plan to cross into mainland China, you need a separate China data plan.