And just today L3 announced more details of their L3 Lynx ADS-B products,
they do apparently include non-TSOed but TSO performance meeting GPS
devices... details are very thin. MSRP is $3,200 for a display less UAT Out
and In box (there is a cheaper UAT Out only box but no pricing yet) and
$6,800 for a Mode S/1090ES Out/1090ES In/UAT In box. All include a
built-in GPS source. The transponder packaging and power consumption are
likely to be quite unsuitable for use in gliders even if somebody wanted to
spend $6,800 plus installation costs. For the GA users this is targeted at
these products may be compelling, especially for older aircraft not
equipped with an IFR/WAAS GPS and an old (high risk if needing repair)
transponder. And I expect prices to drop further as 2020 approaches.

L3 refer to the included internal GPS in these devices as a "Rule Compliant
Position Source"... in other words that GPS is not TSOed but does "meet the
performance requirements of..." (likely TSO-C145c). So you do see effects
of that all that CFR14 91 "meets performance of..." wording here, no word I
could find on the actual TSO status of the boxes themselves. If L3 do not
TSO them expect a pile of confusion/arguments out there in GA A&P land...