Portland, Oregon deal analysis - or situation analysis?

[Jennifer Smith]

Given the following factors, what would be the best way to set myself up for long-term financial stability? Warning: possible dumb questions ahead, I’m new.

* I have a stable job making a little over $100k a year, and excellent credit

* I have a house in Portland, OR for which I paid $301k, I now have approximately $100k in equity. The house has an apartment in the basement that I rent for $800/month. It is not an ADU, the tenant of the apartment is legally my roommate, but they have their own entrance, bathroom and kitchenette.

* I do not want to live in this house long-term, I’d rather move to a nicer neighborhood.

* I am willing to do the work of being a landlord, keeping up the property, etc.

Should I:

a) Sell the house, buy a new house that also has an apartment in the basement, to rent out for help with the mortgage;

b) Stay in the house for a few more years, take out a loan and build an ADU on the property, rent out the basement apartment and the ADU; allowing me to save money on housing costs (my housing costs will go from 1080/month to $50/month with an ADU out back)

c) take out a HELOC and use that for a down payment on a new place (single or multi-family, or house with rentable basement unit like I have now). Will they even let me do that, take out a mortgage on a new place and also have a loan on my current one?

- if I do rent out my old place, should I rent it out as one unit at approx $1880 market (which is exactly my mortgage payment) or can I rent it separately, for $1500 and $800? How does one do that legally?

d) Something else that I haven’t thought of yet?

Assume no family money, not a ton of savings, nobody aside from banks who is willing to loan me money.

Obviously what I'd like to do is buy the new place, put the ADU on my old place and rent it out, but nobody would give me a mortgage/loan combo for that much.

Thank you in advance for your wise counsel!