Double-check the visiting hours of your sights a few days before you leave. I believe what you have for Santa Maria della Salute isn't quite right. The church's website (which I acknowledge might not be 100% accurate in these times) shows a 9:30 AM opening time for the basilica and 10:00 AM for the sacristy: https://basilicasalutevenezia.it/orari-e-visite-turistiche/
I've been visiting a lot of websites recently to put together notes for a trip to northern Italy (probably not happening this year). I'm generally seeing places open; some of the less-heavily-trafficked ones might not be open as many days a week as usual. You're lucky and/or smart with your timing. October 1 is a Friday, and that would be an odd day for places (other than Jewish sights) to close. I think you'll be OK. The last time I looked the hours for the glass museum on Murano were Thursday-Sunday 11 AM to 7 PM; I believe the museum is usually open 7 days a week, so this is an example of cutbacks still in place. Also on Murano, I think you'll be able to see both the Church of San Pietro Martire and the Basilica of Saints Maria and Donato from 9 AM. There are of course many, many glass showrooms and some production facilities on Murano. Since the showrooms are commercial enterprises, they will generally be open. If you hope to see some actual glass-blowing, note that the glass blowers may all take lunch breaks at about the same time (I wouldn't want to guess what that time would be), so you might want to make that the first order of business if you go to Murano first.
I believe the lace museum on Burano is currently open Thursday-Sunday from 12 noon till 6 PM. I haven't found the opening times for San Martino Vescovo, the church on the same square. Burano is quite a long ride across the lagoon. Just this week I read a report of long waiting lines to board vaporettos, so be aware you may get to and from Burano quite as fast as expected.
The above notwithstanding, it wouldn't be a mistake to spend your third day exploring more of Venice proper.
I imagine Walks of Italy is supplying the tickets for St. Marks and the Doge's Palace. Just in case I'm wrong about that: We had a recent report from an on-the-spot poster who reported long lines at St. Mark's. It seems it now charges an entry for the basilica itself as well as for specific parts of the facility (I think the Pala d'Oro, the Treasury and the museum). As a result, many people who used to just walk right in are not having to go through the ticket line, and I speculate that they may be taking time at the counter to decide what parts of the facility they want to pay for. I'd suggest looking online to see whether you buy the ticket ahead of time and avoid the ticket line.