For some reason it seems to work in the latest version of SSMS (version 19) for both serverless and dedicated SQL pools, see download page here
If you've got Redgate SQL prompt this does not work with the serverless SQL but works fine with the dedicated SQL pool, although it does seem to be more 'flaky' than when using it with a normal Azure SQL database. So I use SQL prompt with SSMS version 18 for normal Azure SQL database work and then I use SSMS version 19 without SQL prompt (just using normal SSMS intellisense) for Synapse work.
Also, if you're using Azure Data Studio, the intellisense works fine in there too. Got to admit I'm starting to use that more and more now, eventually I could see moving to that over SSMS... Which I get the feeling Microsoft is slowly 'wanting' to do ;-)
One thing maybe to keep in mind is that even though it works with this version of SSMS, Microsoft don't officially say it does, so its possible it could stop working or break in a future update/version! So make hay while the sun shines as they say...