As you might expect, it has been kind of nuts with gov't instructions changing by the day. I've been waiting to see if I could send out something definitive as anything I write can be inaccurate an hour later. This is what I can tell you so far... Please be sure to check Rocky Point 360 (vs. Facebook groups for possibly unsubstantiated opinions).
The US/Mexico border is the same as it has been--Americans are able to drive southbound into Mexico, and citizens will have no problems reentering the US.
There are only a few instances of Covid-19 reported in Penasco, and the Mayor and state Governor have started a 3-phase plan to reopen. The target date is June 16th for allowing tourists back and removing the (very strict) town roadblocks into Rocky Point. The beaches "should" open for June 16th as well, but I haven't seen any official press release. The municipal government plans to have a thermal screening for each person wanting to come into town. If anyone has an elevated temperature, further testing will be administered. Resorts and Hotels are expected to allow only 40% occupancy to encourage social distancing. Please check my site to start making plans as it would be first-come-first-serve