Severance can definitely delay receiving unemployment. Receiving the $1200 stimulus does not, but receiving the PPP funds through your employer would. The latter consequence is causing some employers to not use that loan/grant.
Employer got PPP and I was un-furloughed on April 27th and they have enough runway for us until June 30th when the PPP runs out. Everyone got a sizable paycut, myself 37%.
I work in corporate events / trade-shows / experiential advertising and this whole industry won't survive.