An SSD will definitely be faster not only for the blockchain sync but also with all aspects of performance.
In order to speed up the blockchain, you can seed it by downloading the bitcoin core client either on your desktop PC or another linux box, and once it’s synced, you can power down your Pi, plug in the hard drive to that machine and copy over blocks, chainstate, and indexes and plug the hdd back into your Pi.
This should dramatically increase your sync speed.
Note that if you installed Electrs and you’re using a private wallet like Sparrow to connect to your own node, Electrs will then need to do an index sync. It should still be faster than having your Pi do the sync since it can only go so fast.