If you're in an area where finding something under $300k would be nearly impossible, just sit tight and focus on saving, learning & networking.

Money is always tight when you're starting out, but I'm here to tell you that after 20 or 30 years of landlording, that security deposit will be a rounding error.

There may not be a market crash/correction (or... there may be one), but with more equity in your house, you can refinance, get a lower payment, and then make decisions on what to do with more cash to finance whatever you choose, be it renovate or move.Yeah, inflation... yeah, quality of life... but it's worth weighing the option of holding tight.

It's all math, but if you're not getting enough in rent, you may want to sell (because inventory is extremely tight right now) and buy in a different area where you'll get higher rents.

Or have an extremely tight relationship with the lender?

The fed is literally walking a tight rope

Typically a seller cannot terminate unless the buyer fails to perform somewhere along the way, but there are many deadlines and contingencies in a standard contract that you need to keep your eye on as a buyer to ensure you comply. 

Consider setting a deadline to submit all applications so then you can review all of the applications at once.

Additionally you have the tricky part of finding a replacement property in time to meet the deadlines in a very under-supplied market (at least locally anyway).  

If you had an appraisal contingency, and you backed out of the deal before the contingency deadline, you would be entitled to the earnest money.