Yes, you can use the same blocks in multiple places just create them in the "For All Site" Assets folder and if you already created them in the "For This Site" then just move them into the "For All SItes" folder.
There's a couple of different options that could work
Is it possible to reuse blocks between two roots, say between examplebank.com and examplebank-x.com?
The reason is that the first root instance is a publicly accessible site, and the second is a restricted environment with bit of a complex AD setup. Both roots are owned by a bank, so the branding is somewhat the same and realise that there some blocks we could use from one root, on the other instead of doing the work twice.
I realise this may be impossible since it basically is two different code bases. But figured I would give it a shot ask, anyone in here seen, heard, know how to support this scenario?