Wood Preservative Clear
I prefer the clear version rather than the "cedar tinted" version even though the clear version is $1 more. Apply with plenty of ventilation to get rid of the VOCs, but does not contain particularly bad ingredients so ok to use internally.
Can then put varnish over it...
Varathane 1 gal. Amber Gloss Interior Polyurethane (Case of 2)
$64.92 for 2 gal
Note this is amber color, but might be ok. Currently best bet.
Epifanes varnish very expensive but might be best bet for front door.
Tung oil is also a good solution (also works outside)...
https://smile.amazon.com/gp/product/B007RO1Q5U/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1 $22.98 + $0 + $0 for quart
https://smile.amazon.com/gp/product/B007RO1PJC/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A3L90ILH9AHNA6 $55.99 + $0 + $0 for gallon