Since I was trying to sell my side project I stumbled upon these sites:

https://acquire.com/ https://flippa.com/ https://empireflippers.com/ https://www.microns.io/ https://www.tiny.com/ https://acquirebase.com/ https://tinyacquisitions.com/ https://transferslot.com/ https://www.sideprojectors.com/ https://indiemaker.co/ https://www.motioninvest.com/