This is generally a shove, yes. If I know that both Villains are excessively limpy foldy say near the bubble I can standard open this and get them to fold, but this is a very good spot to open shove.
1- We have an A. If we hit an A we have top pair. If the board bricks out we usually win.
2 - We are suited. This gives is an extra 3% equity to nut spades, a small thing but anything helps at this point.
3 - Our 8 may not be an awesome kicker but it does cut the deck in half which roughly doubles our equity against small pocket pairs. Also a very large stack will call us with any A and we actually dominate roughly half of those.
4 - Our position is decent on the BT. Post-flop position is meaningless to us if we jam. The blinds are the best place to be, but the BT is the next best thing because we still get to see most of the pre-flop action before we commit to jamming this fairly speculative hand.
5 - The action has folded to us. The table is weak so far and only 2 potential callers. If there were 2 limpers, that would be 4 potential callers and kills our fold equity. If someone had opened before us, they have a hand that competes well against A8s. But the blinds are 100% wide here and any stack with 40bb or less will think twice about putting 12bb at risk, so we have strong fold equity. Furthermore, say the SB folds and the BB is very large like 60-80bb, he will call us wide and we will be ahead of most of his range with a good chance to double up.
There is far from a guarantee here but so many things have gone in our favor so far in this hand.
Also, if there are antes, jamming here is probably better than waiting another orbit for a better shot.