You might be in the same situation as me and migrated from a Canon DSLR to a Sony mirrorless camera. I personally decided to make the move because I could still use some and my Canon equipment and did not have to worry about buying thousands of $$$ of brand new gear. So I have been slowly buying native lenses and lighting equipment. I also found a way to keep using my working horse Canon 580 EXII Speedlite using Godox products. I would like to share my setup with you.
First I purchased a Godox XPro-S TTL wireless trigger. This allows me to control several units at the same time via a 2.4G signal when I mount it to my Sony a7III. I want to mention that this combo works fine and the Xpro-S is compatible with the a7III, Godox does not advertise this on their website… The other piece of equipment needed is a receiver like the Godox X1R-C for the Canon Speedlite. (X1 R for receiver – C for Canon). Now I have a trigger that can communicate with my Canon speedlite. I can change anything from the modes to the zoom range straight from the XPro-S trigger mounted on my a7III. The downside is the Canon Speedlite has to be used as a slave. If you are happy with that you can still use your older Speedlite from your older setup for around $50 cdn. Keep in mind that I payed close to $500 cdn when I purchased my 580 EXII years ago.
I also purchased a Godox V860II-S speedlite that can be mounted on my Sony a7III or used as a slave if I trigger it using the XPro-S. It is very easy and affordable to setup a Godox lighting environment. I am very pleased so far and my experience has been very smooth. I highly suggest Godox products if your are in the market for solid lighting equipment without having to break the bank!