In addition you can rollover existing IRAs into a Solo401k.

I haven't done a refi in a while, but I thought the prepay/escrows will roll over. 

In my specfic case, I'm looking to roll over 401k from previous employer into self directed/solo 401k to allow for more REI options. 

@Jonathan Choyce The IRS has published a rollover chart that consists of a matrix that allows you to see if the account type you want to move from is eligible for the account type you want to move to. 

I have $15K in old 401Ks that I could rollover into a SDIRA and I have $15K in cash saved up.

I also read that I could rollover to an IRA and withdrawal without penalty but not sure how long the process would take. 

I would like to have that in my back pocket in case I run into any issues when it comes time to roll over to a mortgage. 

I’d like to purchase it but all my money is in my rollover Ira that I could find the purchase with.

You may avoid the taxes if you deposit the funds in an eligible retirement plan (which includes anIRA) within "3 years and a day" of the date of the COVID-19 distribution (note: compare to a 60-day rollover).

@Neil McCartyIf you are self-employed (i.e. active self-employment earned income separate from your w-2 income) with no full-time w-2 employees, you can set up a Solo 401k and then rollover your 401k funds from your former employer 401k and/or non-Roth IRA.You could then take a loan of up to 50% of the balance not to exceed $50,000.