This is a growing list that I will update as I find more resources! A lot of these sites have resource lists of their own so I don't want to be too redundant. But these will give you a lot to look through!
General
S.C.O.R.E. - https://www.score.org/ - Free business mentors and affordable workshops
Seattle Restored - https://seattlerestored.org/ - Revitalizing unused retail spaces for small businesses and sponsoring short-term pop-ups
Seattle Good Business Network - https://seattlegood.org/ - Supports businesses by connecting them to local resources
Seattle Made - https://www.seattlemade.org/ - An alliance of local manufacturers and businesses
Seattle Office of Economic Development Free Consulting - https://www.seattle.gov/office-of-economic-development/commercial-affordability/accounting-and-business-consulting-program
Artist Specific
4Culture - https://www.4culture.org/ - Funds community and artistic endeavors
Artist Trust - https://artisttrust.org/resources - Grants, workshops, and connecting artists to resources
Artist Up - https://www.artistsup.org/ - Mentorship program
Edmonds Arts Commission - https://www.edmondswa.gov/cms/one.aspx - Weekly bulletin about art opportunities
Equinox Studios - https://equinoxstudios.org/leasing/ - Studio spaces, they can also help artists find housing if you send them an email
Seattle Artists - https://www.seattleartists.com/ - Forum to post about local events and calls for art
Seattle Office of Arts & Culture - https://www.seattle.gov/arts - Weekly newsletter of calls for art, funding, events, and more
Shunpike - https://shunpike.org/ - Business workshops, funding, community opportunities