If your values always have the foot and inch parts, even it they are 0 (for example, 0'-4" or 5'-0"), then this formula would also work...
=SUM(INDEX(TEXTSPLIT(G46,{"'","""","-"}),,{1,3})/{1,12})
If you could have just the foot value without the dash/inches part, then use this formula instead...
It looks like that build is a year old, from December 2022, and is on the Semi Annual channel.
So it would seem that you have some updates to apply. If you do, I think you should get access to all the latest and greatest functions.