Both spinoff films are in early stages, so it’s currently difficult to speculate how Spider-Man may or may not fit into the narrative.
It also sounds like Holland won’t be making any snap decisions about appearing in a spin-off, even if he is asked to participate.
Venom has already been given an October 2018 release date, which means Holland would need to be approached fairly soon if he’s to be a part of filming.
Recent news about the Silver Sable and Black Cat film indicates, however, that current plans are that these spin-offs won’t be connected to the MCU.