Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net loss	$ (44,355)	$ (24,734)	$ (11,216)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation	373	348	383
Stock-based compensation expense	4,310	406	60
Amortization of premiums and discounts on marketable securities, net	9	0	0
Amortization of discounts and loan issuance costs	29	71	73
Noncash interest expense	110	7,027	374
Change in fair value of preferred warrant liability	75	15	0
Changes in operating assets and liabilities:
Prepaid and other assets	(2,444)	(949)	12
Accounts payable and accrued liabilities	5,749	436	780
Accrued compensation	1,838	1,010	127
Operating lease right-of-use assets and liabilities, net	289	(80)	0
Deferred rent	0	0	(7)
Deferred revenue	(3,100)	18,940	(241)
Net cash (used in) provided by operating activities	(37,117)	2,490	(9,655)
Cash flows from investing activities
Purchases of marketable securities	(6,693)	0	0
Purchases of property and equipment	(1,092)	(235)	(49)
Net cash used in investing activities	(7,785)	(235)	(49)
Cash flows from financing activities
Proceeds from issuance of common stock in initial public offering, gross	298,080	0	0
Payment of issuance costs related to initial public offering	(24,026)	0	0
Proceeds from exercise of stock/unit options, net of repurchases	22	65	162
Proceeds from issuance of common stock under employee stock purchase plan	444	0	0
Proceeds from long-term debt, net of issuance costs	0	0	1,994
Payments on long-term debt	(4,683)	(2,800)	0
Distributions to members	0	(106)	0
Proceeds from issuance of Series C convertible preferred stock, net of issuance costs	2,200	72,623	0
Proceeds from issuance of convertible notes, net of issuance costs	0	19,451	2,988
Net cash provided by financing activities	272,037	89,233	5,144
Net increase (decrease) in cash, cash equivalents and restricted cash	227,135	91,488	(4,560)
Cash, cash equivalents and restricted cash at beginning of period	94,578	3,090	7,650
Cash, cash equivalents and restricted cash at end of period	321,713	94,578	3,090
Supplemental disclosure of cash flow information:
Cash paid for interest	571	322	291
Supplemental schedule of noncash investing and financing activities:
Right-of-use assets obtained in exchange for operating lease liabilities	936	807	0
Costs incurred, but not paid, in connection with purchases of property and equipment included in accounts payable and accrued liabilities	118	43	0
Conversion of convertible preferred stock into common stock upon completion of initial public offering	136,920	0	0
Issuance of Series C convertible preferred stock upon conversion of outstanding convertible notes	0	29,510	0
Reclassification of warrant liability to equity due to adjustment from preferred stock warrant to common stock warrant upon completion of initial public offering	$ 120	$ 0	$ 0