TOSLINK Optical Signal Splitting?

You can get passive and active splitters, passive will degrade the signal strength. The signal strength for the active will be dependent on its' circuity.

Don't have any experience with either, if your runs are short passive should be sufficient. 

Maybe explain your actual use case?  What are you going from and to?

I'm going from the optical out of a Sonos to 2 different DACs...

I’m doing it old school / by hand. I have each optical cable into their DACs and have positioned the cables closely at the source for a quick hotswap with very little cable movement. It’s working good, as optical is not the serious listening path anyway... 
But if you can get to everything easy enough for swapping, this is a fine approach. There are some cable holder / organizer thingies out there that could help hold your two cables right at the connection. 

Does anyone have any thoughts on the original question?
If I signal split an optical signal does it halve the signal strength or does it otherwise degrade the signal?
Any recommendations on how I should do it?

optical is pretty much the worst digital interface.  There isn't a good "Y-cable" solution.  However, if you google for "spdif splitter", there are several products that will split and re-transmit the optical cable signal.  Optical cable is a 1-way digital signal, so there is no worry about hand-shaking or communication.  Two items that seem to have good results:
- J-Tech Digital Premium Quality SPDIF TOSLINK Digital Optical Audio 1x3 Splitter  ($21.98 from Amazon)

- Metra ethereal AS-1X3TSPLIT ($29.99 from Crutchfield)

Here’s one I just bought: https://www.tindie.com/products/Beni_Skate/automatic-spdif-opticalrca-audio-switch/