Tanzania is a great country to visit. As with most tropical African countries Covid-19 is not a problem. It is a huge country twice the size of California so the question is perhaps not if to visit but which part.
The obvious choices are in the neighborhood of the big and small wilderness parks such as Serengeti National Park, Maswa Game Reserve, Kigosi Game Reserve, Mozowosi Game Resever, Ugalla River Game Reserve, Kizigo Game Reserve, Rungwa Game Reserve, Msanjesi Game Reserve, Kitulo Plateau National Park, Kipengere Mpanga Game Reserve, Lukwati Game Reserve, Katavi National Park, Luafi Game Reserve, Mahale Mountain National Park, Ibanda Game Reserve, Kimisi Game Reserve, Burigi Game Reserve, Biharamulo Game Reserve, Maswa Game Reserve, Arusha National Park, Selous Park or Mikumi National Park.
Or the great lakes.
Adventures hikers may consider Mount Kilimanjaro National Park.
Divers might like to go the south eastern part of the country.
Or you might want to rent an entire house with its own Indian Ocean beach, food and a private cook.
There are various different types of accommodations, from very local offerings, through camp like offerings to traditional luxurious beach hotels.