I think that the counterpart of Siacoin before was DGB. It's like these two coins have been together and don't get that much hype. Actually, you can always look for any of those coins that you may think comparable or the same as siacoin.
Just visit coinmarketcap.com or coingecko.com
you are wrong mate about DGB, there are so much noises about it because it is almost reach its ATH again in this year while Siacoin is still far away not even 1/10 of its ATH.
if you categorized Siacoin as one of coin that has strong fundamental, then Theta is a coin that has everything for now.
it is crazily hyped and they are about to have their own mainnet. Siacoin will not make any movement for now but Theta will, I strongly recommend you to check this out.