IMHO Suning have 3 choices.
1)Don't sell anyone and attempt to make it as far as possible in the CL (more games played, more revenue), and hope there isn't another wave of COVID. Keeping this team intact is hugely beneficial monetarily as if they continue to win, more people will be attracted to the club. Winning breeds fans/income.
2)They sell Martinez to cover the 80m needed since we purchased him for peanuts. Imho this is the best option. I have spoke to people claiming Martinez is vital to Lukaku's success this season, BUT that isn't true according to every metric I've seen. Martinez relied on Lukaku, as Rom would drag a couple of defenders to him, giving Lau space. Rom assisted Marty more than Marty assisted Marty. It is also much easier to find a replacement for Martinez. People claim his tenacity for the ball, but Raspadori is actually much much better at it (there's your replacement).
3)Sell a majority stake in the club as they won't be able to cover any costs associated with the club. The loan from Oaktree was a stopgap measure that covers transfer-fees owing, wages, expenses etc.
As for the topic, I wouldn't sell Hakimi for less than 100m, we paid 45m for him and selling him for 80m still doesn't cover our 80m target, meaning someone else needs to be moved. It took us 11 fucking years to find a wingback that was even half capable of doing anything. Here we have Hakimi, a player that was only surpassed by Gosens who is older and has played longer in this league. Hakimi may not be the most defensively capable wingback but that isn't an issue as we do have the best 3 CB's in the league (fewest goals allowed 2nd year in a row).
To me it's not a question about the money, it's about his replacement. There is no one 25 and younger that is better than him, and in my eyes, you only sell a player if you have a replacement that is of equal or greater talent/skill otherwise you are taking 2 steps back to move half a step forward.
Sell Martinez for 100m to Barca (take it in installments), sell Vecino to Napoli for whatever and call it a transfer window.