This weekend is the last weekend for most Tahoe area ski resorts (if they're not already closed). So officially the start of mud season.
Many businesses close or reduce hours significantly during this time, but as with this year of Covid, that may not be the case. During all of Covid, many people form the Bay Area escaped to Tahoe for some outdoor recreation. I think that will probably continue into the summer high season because it is a close by escape for many of us.
There were a lot of crowds this past winter, but many things people come to Tahoe to do are outdoors, so you really only have to be concerned in busy, crowded places like around Heavenly Village.
Restaurants are open for indoor or outdoor dining, and even takeaway. However, if you want to sit down in a restaurant, make a reservation, because they are all spaced for social distancing, so are operating at reduced capacities.
Other than dining and shopping, you can control the crowd situation by partaking of all the lovely outdoor activites available to you. Since its early in the spring season, if you expect to hike, you will encounter snow with any elevation. Want to just walk around the lakefront? -- you won't need waterproof footwear.
The casinos are open for business, but I can't speak to their Covid protocols as I haven't been near one. But just driving by, I can see that they are busy.