Return first element of each cell

I have a table like this:

And I’d like an output like this:

I need to join a table of recipient data using the recipient IDs. Thankfully, the necessary data will be the same for every recipient in the row, so I only need one ID. I want to return the same data, except with only the first (or even just one) ID for each row in the recipient column.

My current method is like this:

SELECT Id,
       Description,
       Recipient,
       MAX(value) as RecipientID
FROM msg 
CROSS APPLY STRING_SPLIT(Recipient, ',')
GROUP BY Id, Description, Recipient

While this method gives me a single recipient ID that I can then use as a key, it takes quite a long time since the recipient column could have a list of IDs larger than 2k in one cell.

I have tried a REGEX solution to extract the starting set of numbers in front of the delimiter, but I couldn’t find a way to do it that wasn’t being used as a filter.

It’d be great if SQL Server had a function like MySQL’s SUBSTRING_INDEX to just get the first ID, but it doesn’t.

How could I go about only returning the one element of each recipient cell without having to do a CROSS APPLY and aggregating?