How close are Leap 15.3 and SLE 15 SP3? Can I use one's rpms with the other?

Apologies if this is a stoopid question. With some effort I have managed to install openSUSE Leap 15.3 on my laptop. As you may know 15.3 is rather different to earlier releases in that it apparently "uses binaries from" SLE 15 SP3. Unfortunately, another difference appears to be that many packages which were there all the way up to 15.2 appear to be missing, I've seen the line [There is no official package available for openSUSE Leap 15.3](https://software.opensuse.org/package/llvm) (this example is llvm) way more often than I care. So my question: Is it generally possible / safe to use SLE 15 SP3 repositories instead? (I see that one of the automatic update repositories is indeed SLE.) I daren't simply try for fear of damaging my system.