UL/CE/CSA certification for low voltage electronics/LED product?
I can only give some ideas for CE marking: -

It seems likely you can self-certify for CE but you need to create a technical file/document that justifies that your product meets the relevant directives and that any testing you have done is applicable and results indicate an acceptable "pass".

At 24V, you are within the voltage limits of the "Low voltage directive" so this doesn't apply BUT you should specify that a power supply that is CE marked is used.

However, you may be subject to the EMC directive in which case you have to justify why the limited tests you may apply justify not conducting full EMC testing.

There are a bunch of other directives that probably won't apply but it is down to you to specify which ones do and which ones don't AND, in the technical document justify why your product meets those various directives.

You also need to draft up a certificate that states all this stuff. There are examples on the web and there are good guidelines: -

UK government website for CE marking

guide on CE marking