I'd be okay with Gyokeres for the right fee this summer but I do think we should be looking at Sesko and Ekitike as first options behind Isak. Like @CPM said, I don't think any of Gyokeres/Sesko/Ekitike is immediately displacing Havertz and they might not displace him at all over the next 1-2 seasons. Isak would be the difference there of course but I'm not holding my breath.
My squad building bias would be to take the younger player with a higher ceiling as a bench/rotation option at striker and Sesko and Ekitike clearly have that advantage over Gyokeres. Gyokeres does have the production that both of them don't have as much of but I'm dubious of the Portuguese league. He has shown glimpses of this in the Champs League (hat trick against City and looking dangerous against us) but I don't think its a done deal that he would be able to replicate that form in the EPL.
That being said, if we came out of this summer with a combination of Gyokeres/Williams/Zubimendi/Nypan, I do think we are a better team next year. I would just prefer to take a chance on the younger prospect rather than the striker coming from a lesser league with production.